VP9: Eliminate extra mv clamp in decoder

The mv is clamped in dec_find_mv_refs() to a smaller region
than the clamp in dec_find_best_ref_mvs().  See clamp_mv_ref
and clamp_mv2.

Change-Id: I47dd5f7fa8b42f2cc593559b4d7c782fe7bcb1db
1 file changed