vp9: Don't force block size to 8x8 in denoiser.

First, we only set use_4x4_partition for key frame where we don't
denoise; second, envision we have small partitions, we should pass the
actual block size to denoiser and make an early termination if needed.

Change-Id: I331f42046d792b17360723d17ff817d601394658
1 file changed