[media] mb86a16/mb86a20s: fix sparse warnings

drivers/media/dvb-frontends/mb86a16.c:31:14: warning: symbol 'verbose' was not declared. Should it be static?
drivers/media/dvb-frontends/mb86a20s.c:36:4: warning: symbol 'mb86a20s_subchannel' was not declared. Should it be static?
drivers/media/dvb-frontends/mb86a20s.c:1333:24: warning: symbol 'cnr_qpsk_table' was not declared. Should it be static?

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