Move MBEDTLS_ERR_xxx Doxygen comments before the definition

Now that descriptions of error codes no longer have to be on the same line
for the sake of generate_errors.pl, move them to their own line before the
definition. This aligns them with what we do for other definitions, and
means that we no longer need to have very long lines containing both the C
definition and the comment.

```
perl -i -pe 's~^(#define +MBEDTLS_ERR_\w+ +-\w+) */\*[*!]<(.*)\*/~/**$2*/\n$1~' include/mbedtls/*.h
```

This commit does not change the output of generate_errors.pl.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/sha512.h b/include/mbedtls/sha512.h
index 4a8ab42..cca47c2 100644
--- a/include/mbedtls/sha512.h
+++ b/include/mbedtls/sha512.h
@@ -34,8 +34,10 @@
 #include <stdint.h>
 
 /* MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED is deprecated and should not be used. */
-#define MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED                -0x0039  /**< SHA-512 hardware accelerator failed */
-#define MBEDTLS_ERR_SHA512_BAD_INPUT_DATA                 -0x0075  /**< SHA-512 input data was malformed. */
+/** SHA-512 hardware accelerator failed */
+#define MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED                -0x0039
+/** SHA-512 input data was malformed. */
+#define MBEDTLS_ERR_SHA512_BAD_INPUT_DATA                 -0x0075
 
 #ifdef __cplusplus
 extern "C" {