Don't consider RIPEMD160 a PSA_ALG_ANY_HASH candidate

Some parts of the library don't support it, such as RSA PKCS#1v1.5
signature.

Author: gilles-peskine-arm

tests/suites/test_suite_psa_crypto.function

@@ -293,8 +293,8 @@ static int exercise_signature_key( psa_key_handle_t handle,
         hash_alg = PSA_ALG_MD4;
 #elif defined(MBEDTLS_MD5_C)
         hash_alg = PSA_ALG_MD5;
-#elif defined(MBEDTLS_RIPEMD160_C)
-        hash_alg = PSA_ALG_RIPEMD160;
+        /* MBEDTLS_RIPEMD160_C omitted because Mbed TLS doesn't
+         * support it in RSA PKCS#1v1.5 signatures. */
 #elif defined(MBEDTLS_SHA1_C)
         hash_alg = PSA_ALG_SHA_1;
 #elif defined(MBEDTLS_SHA256_C)