msm: vidc: Update the mbs per second calculation formula

Currently mbs per second is calculated using height and width
which are the maximums of input and output ports. In rotation
case this logic may end up picking height as both height and
width. Instead using input and output mbs per frame to calculate
mbs per second.

Change-Id: Id53b3ae112645a6ba600597c61401193984e1162
CRs-Fixed: 726903
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>