Make sure Vec256 int32_t and int16_t loadu temprary arrays are properly initialized (#34281)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34281
Seems like #32722 has missed two loadu functions
Test Plan: Imported from OSS
Differential Revision: D20287731
Pulled By: albanD
fbshipit-source-id: d959b2508de3f9f660368152d7260026d7fbccbe
