VP9 common for ARMv8 by using NEON intrinsics 05

Add vp9_iht4x4_add_neon.c
- vp9_iht4x4_16_add_neon

The assembly did not previously implement tx_type 0
BUG=715

Change-Id: I60034d1568de034edba45c5cdd13f3d87dbc73b6
Signed-off-by: James Yu <james.yu@linaro.org>
5 files changed