!5457 Fix logic in distribution utils common_dtype to support tensor inputs

Merge pull request !5457 from XunDeng/pp_issue_branch

mindspore/nn/probability/distribution/_utils/utils.py

@@ -379,8 +379,12 @@ def common_dtype(arg_a, name_a, arg_b, name_b, hint_type):
     if hasattr(arg_a, 'dtype') and hasattr(arg_b, 'dtype'):
         if isinstance(arg_a, np.ndarray):
             a_dtype = mstype.pytype_to_dtype(arg_a.dtype)
-        if isinstance(arg_a, np.ndarray):
+        else:
+            a_dtype = arg_a.dtype
+        if isinstance(arg_b, np.ndarray):
             b_dtype = mstype.pytype_to_dtype(arg_b.dtype)
+        else:
+            b_dtype = arg_b.dtype
         if a_dtype != b_dtype:
             raise TypeError(f"{name_a} and {name_b} should have the same dtype.")
         int_type = mstype.int_type + mstype.uint_type