[media] redrat3: fix sparse warning

Fix this sparse warning:

drivers/media/rc/redrat3.c:490:18: warning: incorrect type in assignment (different base types)
drivers/media/rc/redrat3.c:495:9: warning: cast to restricted __be32

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