[media] v4l: omap4iss: Cancel streaming when a fatal error occurs

When a fatal error that prevents any further video streaming occurs in a
pipeline, all queued buffers must be marked as erroneous and new buffers
must be prevented from being queued. Implement this behaviour with a new
omap4iss_pipeline_cancel_stream() function that can be used by
submodules to cancel streaming.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>