iwlwifi: 4965 define firmware file name once

Apply same idiom as in 5000 introduced by
'iwlwifi: define firmware file name once'

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed