[media] cxd2820r_core: fix sparse warnings

drivers/media/dvb-frontends/cxd2820r_core.c:34:32: error: cannot size expression
drivers/media/dvb-frontends/cxd2820r_core.c:68:32: error: cannot size expression

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>