media: rc: use ktime accessor functions

Prefer using accessor functions so we are not dependent on the ktime_t
type.

Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>