net: introduce IFF_UNICAST_FLT private flag

Use IFF_UNICAST_FTL to find out if driver handles unicast address
filtering. In case it does not, promisc mode is entered.

Patch also fixes following drivers:
stmmac, niu: support uc filtering and yet it propagated
	ndo_set_multicast_list
bna, benet, pxa168_eth, ks8851, ks8851_mll, ksz884x : has set
	ndo_set_rx_mode but do not support uc filtering

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
index f97afda..7c280e5 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
@@ -1080,6 +1080,8 @@
 	netdev->vlan_features |= NETIF_F_HW_CSUM;
 	netdev->vlan_features |= NETIF_F_SG;
 
+	netdev->priv_flags |= IFF_UNICAST_FLT;
+
 	adapter->en_mng_pt = e1000_enable_mng_pass_thru(hw);
 
 	/* initialize eeprom parameters */