[mlir][linalg][transform][python] Simplify mix-in of PadOp.

[ingomueller-net]

Summary

This patch removes some manual conversion of mixed Python/attribute
arguments to I64ArrayAttrs, which turned out to be unnecessary.
Interestingly, this change does not depend on the additional attribute
builders added in the (currently pending)
https://reviews.llvm.org/D159403 patch.

[ftynse]

Consider using Github for future patches, we are moving away from Phabricator.

[ingomueller-net]

Oh, yeah, thanks for the reminder! Will do!

mlir/python/mlir/dialects/_structured_transform_ops_ext.py

def __init__(
         pack_paddings: OptionalIntList = None,
         transpose_paddings: Optional[
             Union[ArrayAttr, Sequence[Union[ArrayAttr, IntOrAttrList]]]
         ] = None,
         copy_back_op: Optional[Union[str, StringAttr]] = None,
         loc=None,
         ip=None,
     ):
-        padding_dimensions = _get_int_array_attr(padding_dimensions)
-        pad_to_multiple_of = _get_int_array_attr(pad_to_multiple_of)
-        pack_paddings = _get_int_array_attr(pack_paddings)
         transpose_paddings = _get_int_array_array_attr(transpose_paddings)
 
         pdl_operation_type = pdl.OperationType.get()
         super().__init__(
             pdl_operation_type,
             pdl_operation_type,
             pdl_operation_type,
             target,