Rework the txfm partition context to support cb4x4 mode

This commit reworks the transform block partition context update
to support cb4x4 mode in the recursive transform block partition.
It resolves the remaining enc/dec mismatch issue when both cb4x4
and var-tx are turned on.

Change-Id: I850d121204fe4c68e81488f1d2848c570d9d08b9
6 files changed