media: omap3isp: Don't restart CCDC if we're about to stop

The omap3isp driver set the new buffer and enabled the CCDC in a situation
a new buffer was available but streaming was about to be stopped on the
CCDC. This lead to frequent system crashes in case there were buffers
queued when streming was being stopped.

Fix this by first checking whether there's an intent to stop streaming and
if there isn't, then set the new buffer and re-enable CCDC.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>