Stop using SkSwizzler in SkRawCodec

Bug: skia:8473

SkRawCodec doesn't implement scanline decoding or incremental decoding,
so it doesn't take advantage of SkSwizzler's sampling. It just uses it
to do conversion, and then it potentially uses skcms to transform
colors. Instead, always use skcms and avoid creating the SkSwizzler.

Change-Id: Ie0d4f83b0eac18150a6d52382c8283babb6cbfca
Reviewed-on: https://skia-review.googlesource.com/c/175592
Commit-Queue: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Auto-Submit: Leon Scroggins <scroggo@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2 files changed