Fix cuda launch error in reflection_pad2d (#56451)
Summary:
Fix https://github.com/pytorch/pytorch/issues/55222
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56451
Reviewed By: malfet
Differential Revision: D27912184
Pulled By: ngimel
fbshipit-source-id: 3fc80273c30a68a247289d3fb698f99b92931731
