Fix YUVA index check

Bug: skia:7901
Change-Id: If43eb80e1c8ab25074b1e0fda68139d4e6c44729
Reviewed-on: https://skia-review.googlesource.com/c/162020
Auto-Submit: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
1 file changed