Fix duplication of the type check

Author: tino097

mindsdb_sql_parser/parser.py

@@ -126,7 +126,7 @@ def create_kb(self, p):
         model = params.pop('model', None)
         storage = params.pop('storage', None)
 
-        if isinstance(model, str):
+        if isinstance(storage, str):
             # convert to identifier
             storage = Identifier(storage)