[media] v4l: omap4iss: Propagate stop timeouts from submodules to the driver core

Return an error from the s_stream handlers when stopping the stream
failed instead of just logging the error and ignoring it. While we're
at it, move the logging code from submodules to the driver code.

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