Fix vp9_quantize_fp(_32x32)_neon for HBD

In high bitdepth build, Neon code would outrange because of use of
int16x8_t and vmulq_s16.
C code always truncate outrange values.

Change-Id: I33a968b8d812e3c8477f3a61d84482758a3f8b21
1 file changed