Don't set BASE/MAX mip map level on PowerVR.

Speculative fix for Chrome crashes.

Implemented by separating out LOD and level caps.

Also don't allow GrContextOptions to enable manual mip mapping
if level control is not available.

Change-Id: Ibdf647792e1e018efeffa0af34ceb59e751e6749
Bug: chromium:1123874
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/315638
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
4 files changed