Make \retval commands non-empty

Pacify Clang >=15 which complained:
```
include/psa/crypto.h:91:23: error: empty paragraph passed to '\retval' command [-Werror,-Wdocumentation]
 * \retval #PSA_SUCCESS
   ~~~~~~~~~~~~~~~~~~~^
```

This commit performs the following systematic replacement:
```
perl -i -0777 -p -e 's/([\\@])(retval +\S+)\n(?! *\*? *([^\n \\*\/]|\\[cp]\b))/$1$2 ${1}emptydescription\n/g' $(git ls-files '*.[hc]' '*.function' '*.jinja')
```
i.e. add an `\emptydescription` argument to `\retval` commands (or
`@retval`, which we don't normally used) that are followed by a single word,
unless the next line looks like it contains text which would be the
description.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/psa_crypto_cipher.h b/library/psa_crypto_cipher.h
index 6cc6bf6..bf43ff0 100644
--- a/library/psa_crypto_cipher.h
+++ b/library/psa_crypto_cipher.h
@@ -59,10 +59,10 @@
  *                              (\c PSA_ALG_XXX value such that
  *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
  *
- * \retval #PSA_SUCCESS
- * \retval #PSA_ERROR_NOT_SUPPORTED
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ * \retval #PSA_SUCCESS \emptydescription
+ * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_encrypt_setup(
     mbedtls_psa_cipher_operation_t *operation,
@@ -89,10 +89,10 @@
  *                              (\c PSA_ALG_XXX value such that
  *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
  *
- * \retval #PSA_SUCCESS
- * \retval #PSA_ERROR_NOT_SUPPORTED
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ * \retval #PSA_SUCCESS \emptydescription
+ * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_decrypt_setup(
     mbedtls_psa_cipher_operation_t *operation,
@@ -116,11 +116,11 @@
  *                              the core to be less or equal to
  *                              PSA_CIPHER_IV_MAX_SIZE.
  *
- * \retval #PSA_SUCCESS
+ * \retval #PSA_SUCCESS \emptydescription
  * \retval #PSA_ERROR_INVALID_ARGUMENT
  *         The size of \p iv is not acceptable for the chosen algorithm,
  *         or the chosen algorithm does not use an IV.
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_set_iv(
     mbedtls_psa_cipher_operation_t *operation,
@@ -142,10 +142,10 @@
  * \param[out] output_length    On success, the number of bytes
  *                              that make up the returned output.
  *
- * \retval #PSA_SUCCESS
+ * \retval #PSA_SUCCESS \emptydescription
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p output buffer is too small.
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_update(
     mbedtls_psa_cipher_operation_t *operation,
@@ -165,7 +165,7 @@
  * \param[out] output_length    On success, the number of bytes
  *                              that make up the returned output.
  *
- * \retval #PSA_SUCCESS
+ * \retval #PSA_SUCCESS \emptydescription
  * \retval #PSA_ERROR_INVALID_ARGUMENT
  *         The total input size passed to this operation is not valid for
  *         this particular algorithm. For example, the algorithm is a based
@@ -176,7 +176,7 @@
  *         padding, and the ciphertext does not contain valid padding.
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p output buffer is too small.
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_finish(
     mbedtls_psa_cipher_operation_t *operation,
@@ -195,7 +195,7 @@
  *
  * \param[in,out] operation     Initialized cipher operation.
  *
- * \retval #PSA_SUCCESS
+ * \retval #PSA_SUCCESS \emptydescription
  */
 psa_status_t mbedtls_psa_cipher_abort(mbedtls_psa_cipher_operation_t *operation);
 
@@ -224,10 +224,10 @@
  *                              the returned output. Initialized to zero
  *                              by the core.
  *
- * \retval #PSA_SUCCESS
- * \retval #PSA_ERROR_NOT_SUPPORTED
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ * \retval #PSA_SUCCESS \emptydescription
+ * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED \emptydescription
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p output buffer is too small.
  * \retval #PSA_ERROR_INVALID_ARGUMENT
@@ -275,10 +275,10 @@
  *                              the returned output. Initialized to zero
  *                              by the core.
  *
- * \retval #PSA_SUCCESS
- * \retval #PSA_ERROR_NOT_SUPPORTED
- * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
- * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ * \retval #PSA_SUCCESS \emptydescription
+ * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription
+ * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED \emptydescription
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p output buffer is too small.
  * \retval #PSA_ERROR_INVALID_ARGUMENT