ARM Skia NEON patches - 23 - S32_D565_Opaque_Dither cleanup/bugfix/speed

ARM Skia NEON patches - 23 - S32_D565_Opaque_Dither cleanup/bugfix/speed

BlitRow565: S32_D565_Opaque_Dither: cleaning / bugfix

This patch brings a little code cleaning (spaces/comments) and a little
speed improvement (by using post-incrementation in the asm) but more
importantly it fixes a bug on Linux. The new code now supports ARGB
as well as ABGR.

I removed the comment as I have confirmed with benchmarks that this
code bring a *massive* (3x-7x) speedup compared to the C code.

Signed-off-by: Kévin PETIT <kevin.petit@arm.com>
BUG=
R=djsollen@google.com, mtklein@google.com

Author: kevin.petit.arm@gmail.com

Review URL: https://chromiumcodereview.appspot.com/22269003

git-svn-id: http://skia.googlecode.com/svn/trunk@11339 2bbb7eff-a529-9590-31e7-b0007b416f81