[media] omap3isp: Add missing mutex_destroy() calls

Mutexes must be destroyed with mutex_destroy(). Add missing calls in the
modules cleanup handlers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/omap3isp/ispstat.c b/drivers/media/video/omap3isp/ispstat.c
index b124326..28b7cc6 100644
--- a/drivers/media/video/omap3isp/ispstat.c
+++ b/drivers/media/video/omap3isp/ispstat.c
@@ -1087,6 +1087,7 @@
 void omap3isp_stat_cleanup(struct ispstat *stat)
 {
 	media_entity_cleanup(&stat->subdev.entity);
+	mutex_destroy(&stat->ioctl_lock);
 	isp_stat_bufs_free(stat);
 	kfree(stat->buf);
 }