We managed to disable NPOT textures on AMD. Reenable them.

BUG=angle:799

Change-Id: Iaa8aee1f09c8c2ac3669d6709572f76f40f21847
Reviewed-on: https://chromium-review.googlesource.com/224042
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>