sfc: efx_get_phys_port_id() can be static

Fixes the following sparse warning:

drivers/net/ethernet/sfc/efx.c:2337:5: warning:
 symbol 'efx_get_phys_port_id' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/efx.c

@@ -2334,7 +2334,7 @@ static int efx_set_features(struct net_device *net_dev, netdev_features_t data)
 	return 0;
 }
 
-int efx_get_phys_port_id(struct net_device *net_dev,
+static int efx_get_phys_port_id(struct net_device *net_dev,
 				struct netdev_phys_item_id *ppid)
 {
 	struct efx_nic *efx = netdev_priv(net_dev);