bonding: add rtnl protection for bonding_store_fail_over_mac
bonding: add rtnl protection for bonding_store_fail_over_mac

We need rtnl protection while reading slave_cnt and updating
the .fail_over_mac, and it also follows the logic "don't change
anything slave-related without rtnl". :)

Signed-off-by: Ding Tianhong <6319509b12a56ad4c8f781f7750eb8df2374d4fd@huawei.com>
Cc: Jay Vosburgh <9ab50f27d4201db9b28483ba83c48ebafbb2aa17@us.ibm.com>
Cc: Andy Gospodarek <e3579b1e47f273529f0f929453e939a68ede9fd1@greyhouse.net>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs