media: rc: reduce useless padding in struct rc_dev etc

Reorder the fields in these structs so that we waste less space due to
padding. pahole shows that lirc_fh is 8 bytes smaller, and rc_dev is 32
bytes smaller.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>