[media] exynos4-is: Unregister fimc-is subdevs from the media device properly

Add missing v4l2_device_unregister_subdev() call for the FIMC-IS subdevs
(currently there is only the FIMC-IS-ISP subdev) so corresponding resources
are properly freed upon the media device driver module removal.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyugmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/platform/exynos4-is/media-dev.c

@@ -823,6 +823,10 @@ static void fimc_md_unregister_entities(struct fimc_md *fmd)
 		fimc_md_unregister_sensor(fmd->sensor[i].subdev);
 		fmd->sensor[i].subdev = NULL;
 	}
+
+	if (fmd->fimc_is)
+		v4l2_device_unregister_subdev(&fmd->fimc_is->isp.subdev);
+
 	v4l2_info(&fmd->v4l2_dev, "Unregistered all entities\n");
 }