post_proc: improve logging

Make logs more meaningful and remove
ones not necessary.

Change-Id: I9562cf34a5dee406b1c0347a9004db08de9cd5df
post_proc: disable Bassboost and Virtualizer for USB_ACCESSORY

USB_ACCESSORY is not intended to be applied with SA+ bassboost
and virtualizer, so add into invalid devices list.

CRs-Fixed: 659191
Change-Id: If1f3421f9935ce624dc21895d9244d36d195b2bd
post_proc: fix post and pre process KW issues

KW issue fix includes:
- handle memory allocation failure
- array index boundary check

Change-Id: I083952ba58d348a5b650601a83e6f492b0d686bb