graphite: use the new Features::Unorm16TextureFormats name

wgpu::Features::Norm16TextureFormats is deprecated in dawn. Use the new
feature wgpu::Features::Unorm16TextureFormats instead.

Bug: 331771944
Change-Id: I50ba4879daae1f5ab1b715679ab17cdced5edf40
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5430953


Commit-Queue: Peng Huang <penghuang@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1283575}