Fix select_dtype_combinations return for GenMode.All (#339)

Summary: Pull Request resolved: #339

Reviewed By: larryliu0820

Differential Revision: D49217789

fbshipit-source-id: 959456fca892a60e14592c17eab3d7847433bc68

Author: manuelcandales

exir/dialects/edge/dtype/runner.py

@@ -111,7 +111,8 @@ def produce_code_tuples(n: int, i: int) -> Iterator[Tuple[int]]:
 
         type_tuples = self._get_type_tuples(inputs)
         if genmode == GenMode.All:
-            return itertools.product(*type_tuples)  # noqa
+            for dtype_tuple in itertools.product(*type_tuples):
+                yield dtype_tuple
         elif genmode == GenMode.Partial:
             dtype_tuples_set = set()
             types = DtypeRunner._get_types(inputs)