msm: vidc: Adds bus scaling for video codecs

Adds bus scaling so that the bus bandwidth
can be voted for according to load. This
optimizes power consumption during video
encode and decode operation.

Change-Id: I4b7123e9ae2e429ffe9bf4636d633284768e1b33
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>