Function psa_get_key_policy() now return policy value for empty slots

Function psa_get_key_policy() now return policy value for empty slots
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index c516e38..a253622 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1346,8 +1346,6 @@
         return( PSA_ERROR_INVALID_ARGUMENT );
 
     slot = &global_data.key_slots[key];
-    if( slot->type == PSA_KEY_TYPE_NONE )
-        return( PSA_ERROR_EMPTY_SLOT );
     
     *policy = slot->policy;