[media] s5p-mfc: fix enum_fmt for s5p-mfc

As the s5p-mfc is a driver which use  multiplanar api, so the
vidioc_enum_fmt_vid serial of ioctl should only for
multiplanar, non-multiplanar shouldn't be implemented at all.

Signed-off-by: ayaka <ayaka@soulik.info>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>