[media] s3c-camif: Check if fmt is NULL before use

As reported by smatch:
	drivers/media/platform/s3c-camif/camif-capture.c:463 queue_setup() warn: variable dereferenced before check 'fmt' (see line 460)

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>