allow 4444 sw surfaces

c.f. https://skia-review.googlesource.com/c/skia/+/92681

Change-Id: I0e73ee7fd7b6a6c122121fcaddb7abe2af0b8042
Reviewed-on: https://skia-review.googlesource.com/99301
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
3 files changed