SETUP provided by zhongwei.yao@linaro.org

Previously the 64 bit Neon code had hard coded constants in the setup macro
for YUV conversion, while 32 bit Neon code supported the yuvconstants
parameter.

This change accepts the constants passed to the YUV conversion row function,
allowing different color spaces to be respected - naming JPEG and BT.709.
As well as the existing BT.601.

TBR=harryjin@google.com
BUG=libyuv:472

Review URL: https://codereview.chromium.org/1384323002 .