Optimize CMYK->RGBA (BGRA) transform for jpeg decodes

Swizzle Bench Runtime
Nexus 6P     0.14x
Dell Venue 8 0.12x

CMYK Jpeg Decode Runtime
Nexus 6P     0.81x
Dell Venue 8 0.85x

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1676773003
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Review URL: https://codereview.chromium.org/1676773003
7 files changed