[media] cxusb: fix sparse warning

drivers/media/usb/dvb-usb/cxusb.c:178:40: warning: restricted __le16 degrades to integer

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>