[media] media: mx2-emmaprp: Add missing mutex_destroy()

This patch adds the missing mutex_destroy(), when the driver is removed.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/platform/mx2_emmaprp.c

@@ -985,6 +985,8 @@ rel_vdev:
 unreg_dev:
 	v4l2_device_unregister(&pcdev->v4l2_dev);
 
+	mutex_destroy(&pcdev->dev_mutex);
+
 	return ret;
 }
 
@@ -998,6 +1000,7 @@ static int emmaprp_remove(struct platform_device *pdev)
 	v4l2_m2m_release(pcdev->m2m_dev);
 	vb2_dma_contig_cleanup_ctx(pcdev->alloc_ctx);
 	v4l2_device_unregister(&pcdev->v4l2_dev);
+	mutex_destroy(&pcdev->dev_mutex);
 
 	return 0;
 }