vp9: Fix denoising condition when pickmode partition is used.

vp9: Fix denoising condition when pickmode partition is used.

When the superblock partition is based on the nonrd-pickmode,
we need to avoid the denoising. Current condition was based on
the speed level. This change is to make the condition at the
superblock level, as the switch in partitioning may be done at
sb level based on source_sad (e.g., in speed 6).

Change-Id: I12ece4f60b93ed34ee65ff2d6cdce1213c36de04