vidc: cleanup allocated ion buffers in case of crash.

when a userspace process crashes, the video driver
release function is called and the allocated
ion buffers are cleaned up to avoid memory leaks in case
of userspace process crash.

Change-Id: I538381b08b27adffe64e23dcf479802fc62179a4
Signed-off-by: Deepak Kotur <dkotur@codeaurora.org>