Stop BRD-decoding non-opaque to 565 sink

review.skia.org/34361 accidentally started attempting to decode images
with transparency to a 565 sink. BRD helpfully decodes to N32 instead,
rather than failing. We don't need to test this here, and it draws to a
565 sink, resulting in incorrect images in Gold.

Change-Id: I9585b2c0c4526e5f33667bd8f57003449e735372
Reviewed-on: https://skia-review.googlesource.com/35707
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
1 file changed