V4L/DVB (13481): sh_mobile_ceu_camera: fix compile warning

Trivial fix for this compile warning:

v4l/sh_mobile_ceu_camera.c:1789: warning: label 'exit_free_irq' defined but not used

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>