Remove check for lack of supported ciphers

Add comment explaining (currently) empty function.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/library/psa_crypto_aead.c b/library/psa_crypto_aead.c
index bc37a04..a72865c 100644
--- a/library/psa_crypto_aead.c
+++ b/library/psa_crypto_aead.c
@@ -446,20 +446,12 @@
     size_t ad_length,
     size_t plaintext_length )
 {
-
+    /* Nothing here yet, work is currently done in PSA Core, however support
+     * for CCM will require this function. */
     ( void ) operation;
     ( void ) ad_length;
     ( void ) plaintext_length;
 
-#if !defined(MBEDTLS_PSA_BUILTIN_ALG_GCM) && \
-    !defined(MBEDTLS_PSA_BUILTIN_ALG_CCM) && \
-    !defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
-    {
-        return ( PSA_ERROR_NOT_SUPPORTED );
-    }
-#endif /* !MBEDTLS_PSA_BUILTIN_ALG_GCM && !MBEDTLS_PSA_BUILTIN_ALG_CCM &&
-         !MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305) */
-
     return ( PSA_SUCCESS );
 }