ARM Skia NEON patches - 40 - arm64: S32A_D565_Opaque

ARM Skia NEON patches - 40 - arm64: S32A_D565_Opaque

Here are some perf results:

+-------+------------+------------+
| count | Cortex-A53 | Cortex-A57 |
+-------+------------+------------+
|     1 |     -2.54% |     -5.39% |
+-------+------------+------------+
|     2 |     -0.66% |     -2.08% |
+-------+------------+------------+
|     4 |    -11.13% |      0.00% |
+-------+------------+------------+
|     8 |     -5.79% |     -1.30% |
+-------+------------+------------+
|    16 |     71.60% |     93.27% |
+-------+------------+------------+
|    64 |     30.99% |     57.35% |
+-------+------------+------------+
|   256 |     25.41% |     52.59% |
+-------+------------+------------+
|  1024 |     25.56% |     53.76% |
+-------+------------+------------+

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

Author: kevin.petit@arm.com

Review URL: https://codereview.chromium.org/346843003