msm: vidc: Update validation for operating rate

Allow operating rate to be set to higher value
when clock scaling is disabled or core is voted
at max frequency to cover the DCVS window.

Change-Id: Ice3bd821365b54855bae294699dd44ab34e5a8ea
Signed-off-by: Saurabh Kothawade <skothawa@codeaurora.org>