Update on "[ET-VK] Changing all conv 2d pw ints from uint16 to int since it slightly improves perf."

This diff changes all integers in conv 2d pw op shader from uint16 to int in the Vulkan backend of Executorch. The change is made to improve performance since the shader does not appear to be register bound.

Differential Revision: [D67906023](https://our.internmc.facebook.com/intern/diff/D67906023/)

[ghstack-poisoned]

Author: trivedivivek