[ET-VK] Using uint16 for quantized linear tiling shader to reduce register pressure and improve performance. (#10509)

Stack from [ghstack](https://github.com/ezyang/ghstack) (oldest at
bottom):
* __->__ #10509
* #10508

This diff reduces int precision for certain variables in 8 bit quantized
tiled linear op to reduce register pressure and improve performance.

Differential Revision:
[D73752090](https://our.internmc.facebook.com/intern/diff/D73752090/)

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Co-authored-by: Sicheng Stephen Jia <ssjia@meta.com>