net: bonding: Correct function name bond_change_active_slave() in comment

Fix the following make W=1 kernel build warning:

 drivers/net/bonding/bond_main.c:982: warning: expecting prototype for change_active_interface(). Prototype was for bond_change_active_slave() instead

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>