Remove RAW PSK when MBEDTLS_USE_PSA_CRYPTO is selected

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index 7f725a1..f7cceed 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -160,12 +160,13 @@
     if( conf->psk_identity_len == 0 || conf->psk_identity == NULL )
         return( 0 );
 
-    if( conf->psk != NULL && conf->psk_len != 0 )
-        return( 1 );
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
     if( ! mbedtls_svc_key_id_is_null( conf->psk_opaque ) )
         return( 1 );
+#else
+    if( conf->psk != NULL && conf->psk_len != 0 )
+        return( 1 );
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
     return( 0 );