ARM Skia NEON patches - 25 - S32A_D565_Opaque_Dither clean/bugfix/speed
ARM Skia NEON patches - 25 - S32A_D565_Opaque_Dither clean/bugfix/speed

BlitRow565: S32A_D565_Opaque_Dither: some improvements

    - Supports ARGB and ABGR
    - Less magic numbers
    - Reduced instruction count : 5-25% speedup
    - Fixed indentation, removed some commented and useless code

Signed-off-by: Kévin PETIT <kevin.petit@arm.com>

BUG=skia:
R=djsollen@google.com, mtklein@google.com

Author: kevin.petit@arm.com

Review URL: https://codereview.chromium.org/177963003

Change-Id: I4f6083372e653fda5224b0f74dc5affbaa4c8f8f
git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@13577 2bbb7eff-a529-9590-31e7-b0007b416f81

VanirAOSP/external_skia,VanirAOSP/external_skia,VanirAOSP/external_skia,VanirAOSP/external_skia,VanirAOSP/external_skia