msm: vidc: venus_boot: Check for clock set rate

Add a check similar to vidc driver to make sure
not to call clk_set_rate on clocks that can't be
controlled externally.

Change-Id: Ic8e5871245d3939de0876fbd707a71594f461c09
Signed-off-by: Sachin Shah <sachins@codeaurora.org>