Remove GrPixelConfigIsCompressed call.

Bug: skia:6718
Change-Id: Ia6363d74f016b076fa5e19a57d223f7c47b723c0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/248999
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
4 files changed