msm: vidc: Send ABORT in FLUSH command from the client

When session error is sent to the client, client issues FLUSH
and release buffers commands. But as instance state is INVALID,
these commands are never sent to the firmware, instead FLUSH
DONE and Release buffer done are sent back to client even
though firmware might be working on these buffers which may
result into page faults.
This change fixes the issue by sending ABORT command to the
firmware at the time when driver receives FLUSH command. Then
firmware will release all buffers, clean up session and send
ABORT_DONE back to the driver.

CRs-fixed: 592920
Change-Id: Ie4c79a312d2336c68b858f5f5e2a85331cf55f7b
Signed-off-by: Deepak Verma <dverma@codeaurora.org>