[media] bcm3510: fix sparse warnings

drivers/media/dvb-frontends/bcm3510.c:646:24: warning: cast to restricted __le16
drivers/media/dvb-frontends/bcm3510.c:647:24: warning: cast to restricted __le16

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