msm: vidc: Handle SYS_IDLE interrupt concurrency

It is possible to receive SYS_IDLE message before
Venus core sends the interrupt for that message.
This results in clocks not being disabled at all
and device will continue to drain power.

This change checks when the interrupt is received
if the venus core is still in IDLE state. If it is
then disable the clocks.

Change-Id: If2b8d778054a702eada40ac3588e2ec3a3fbd80a
CRs-fixed: 548745
Signed-off-by: Sachin Shah <sachins@codeaurora.org>