I422ToRGB565Row_Any_AVX2 uses 2 step row conversion that calls
I422ToARGBRow_AVX2 and then ARGBToRGB565.
I422ToARGBRow_AVX2 expects multiple of 16 pixels.
Adjust the I422ToRGB565Row_Any_AVX2 to do multiple of 16 with AVX2
and then remainder in a buffer.

Bug: libyuv: 657
Test: out/Release/libyuv_unittest --gtest_filter=*Convert*I*To* --libyuv_width=1280 --libyuv_height=720
Change-Id: Ice1cb6c7ff6b2295513e8b4a9f77522e1c659810
Reviewed-on: https://chromium-review.googlesource.com/474232
Commit-Queue: Frank Barchard <fbarchard@google.com>
Reviewed-by: Henrik Kjellander <kjellander@chromium.org>