[media] cobalt: fix sparse warnings

[media] cobalt: fix sparse warnings

drivers/media/pci/cobalt/cobalt-flash.c:101:5: warning: symbol 'cobalt_flash_probe' was not declared. Should it be static?
drivers/media/pci/cobalt/cobalt-flash.c:126:6: warning: symbol 'cobalt_flash_remove' was not declared. Should it be static?
drivers/media/pci/cobalt/cobalt-cpld.c:101:6: warning: symbol 'cobalt_cpld_status' was not declared. Should it be static?
drivers/media/pci/cobalt/cobalt-cpld.c:240:6: warning: symbol 'cobalt_cpld_set_freq' was not declared. Should it be static?

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