cros_gralloc: Use entire graphics buffer if all-zeros access region is specified

cros_gralloc: Use entire graphics buffer if all-zeros access region is specified

This is a requirement of gralloc and the graphics.mapper HAL in Android.

BUG=b:143924619
TEST=Photo capture in GCA succeeds and most camera CTS tests pass

Change-Id: Ic34a49aa7175c1c3b9f6c0738b5ab848e002b93d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/2035207
Tested-by: Matthias Springer <springerm@chromium.org>
Commit-Queue: Matthias Springer <springerm@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: David Stevens <stevensd@chromium.org>
Auto-Submit: Matthias Springer <springerm@chromium.org>