Extension:CentralNotice/cn notice mobile carriers table

mysql> describe cn_notice_mobile_carriers; ++-+--+-+-++ ++-+--+-+-++ ++-+--+-+-++
 * Field | Type    | Null | Key | Default | Extra          |
 * nmc_id | int(11) | NO  | PRI | NULL    | auto_increment |
 * not_id | int(11) | NO  | MUL | NULL    |                |
 * mc_id | int(11) | NO   | MUL | NULL    |                |