bonding: netpoll: remove unwanted slave_dev_support_netpoll()

The __netpoll_setup() will check the slave's flag and ndo_poll_controller just
like the slave_dev_support_netpoll() does, and slave_dev_support_netpoll() was
not used by any place, so remove it.

Cc: Jay Vosburgh <fubar@us.ibm.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: NDing Tianhong <dingtianhong@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -942,14 +942,6 @@ static inline void slave_disable_netpoll(struct slave *slave)
 	slave->np = NULL;
 	__netpoll_free_async(np);
 }
-static inline bool slave_dev_support_netpoll(struct net_device *slave_dev)
-{
-	if (slave_dev->priv_flags & IFF_DISABLE_NETPOLL)
-		return false;
-	if (!slave_dev->netdev_ops->ndo_poll_controller)
-		return false;
-	return true;
-}
 
 static void bond_poll_controller(struct net_device *bond_dev)
 {