msm: vidc: Scale bus bw along with venus clocks

Scaling of Bus BW and Venus Clocks should go together.
Otherwise the benefits of reducing voltage corner will be
nullified, since VMEM vote remains high.

CRs-Fixed: 1083761
Change-Id: Ib38ecabb3c4bf40fcf5ad368fbbdbe4c44edbf3b
Signed-off-by: Chinmay Sawarkar <chinmays@codeaurora.org>