Only accept RSA key pair in mbedtls_pk_setup_opaque()

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/library/pk.c b/library/pk.c
index 837d6a2..9b16eca 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -169,7 +169,7 @@
 
     if( PSA_KEY_TYPE_IS_ECC_KEY_PAIR( type ) )
         info = &mbedtls_pk_ecdsa_opaque_info;
-    else if( PSA_KEY_TYPE_IS_RSA( type ) )
+    else if( type == PSA_KEY_TYPE_RSA_KEY_PAIR )
         info = &mbedtls_pk_rsa_opaque_info;
     else
         return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );