msm: vidc: Force vmem_maxi_clk to certain frequencies for 4K sessions

For 4K encode sessions, we'd like vmem_maxi_clk to run at 320Mhz.  On
the flip side for 4K decode session, we'd like to force the frequency
to 100 Mhz (30 fps) or 320 Mhz (60 fps).

Change-Id: I0337b5ebfb47c62997a28bc11a99d146250d447a
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>