Fix a bug in calculating delta in VP9 denoiser.

When calculating delta in VP8 denoiser, since the block size is fixed to 16x16,
the divisor is 256, which is the number of the pixel.
But in VP9, the block size varies, the divisor should correspond to the block
size.

Change-Id: Ibdc1e5d23ba8c788b0d0dc6d406bcdfc34c1b142

vp9/encoder/vp9_denoiser.c

diff --git a/vp9/encoder/vp9_denoiser.c b/vp9/encoder/vp9_denoiser.c
index 681b2a5..11cb27f 100644
--- a/vp9/encoder/vp9_denoiser.c
+++ b/vp9/encoder/vp9_denoiser.c
@@ -143,7 +143,7 @@
 
   // Otherwise, we try to dampen the filter if the delta is not too high.
   delta = ((abs(total_adj) - total_adj_strong_thresh(bs, increase_denoising))
-           >> 8) + 1;
+           >> num_pels_log2_lookup[bs]) + 1;
 
   if (delta >= delta_thresh(bs, increase_denoising)) {
     return COPY_BLOCK;