msm: vidc: Mask interrupts from venus after receiving IDLE message

IDLE message from venus indicates that the venus is idle and its
clocks are turned off. These clocks should not be turned on by any
pending or spurious(interrupts without any message) interrupts to save
power.

Change-Id: I622212a7e8c51106fbf69c491d129f219eb6ce54
CRs-fixed: 583989
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>