[media] az6027: fix sparse warnings

drivers/media/usb/dvb-usb/az6027.c:257:23: warning: symbol 'az6027_stb0899_config' was not declared. Should it be static?
drivers/media/usb/dvb-usb/az6027.c:294:23: warning: symbol 'az6027_stb6100_config' 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>