Remove redundant check arr_or_dtype is None (pandas-dev#26655)

Author: AlexTereshenkov

pandas/core/dtypes/common.py

@@ -1931,8 +1931,6 @@ def _is_dtype_type(arr_or_dtype, condition):
         if issubclass(arr_or_dtype, ExtensionDtype):
             arr_or_dtype = arr_or_dtype.type
         return condition(np.dtype(arr_or_dtype).type)
-    elif arr_or_dtype is None:
-        return condition(type(None))
 
     # if we have an array-like
     if hasattr(arr_or_dtype, 'dtype'):