[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/isp.c b/drivers/media/video/omap3isp/isp.c
index 678e125..c8f147e 100644
--- a/drivers/media/video/omap3isp/isp.c
+++ b/drivers/media/video/omap3isp/isp.c
@@ -2210,6 +2210,8 @@
 	regulator_put(isp->isp_csiphy2.vdd);
 	regulator_put(isp->isp_csiphy1.vdd);
 	platform_set_drvdata(pdev, NULL);
+
+	mutex_destroy(&isp->isp_mutex);
 	kfree(isp);
 
 	return ret;