media: s5p-mfc: fix usage of symbolic permissions to octal

Change symbolic permissions to octal equivalent as recommended
by scripts/checkpatch.pl in drivers/media/platform/samsung/
s5p-mfc/s5p_mfc.c.

Signed-off-by: Aakarsh Jain <aakarsh.jain@samsung.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>