[media] media: s5p-cec: Remove unneeded linux/miscdevice.h include

s5p-cec: does not use any miscdevice so this patch remove this
unnecessary inclusion.

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>