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/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 40d4c40..592b5c1 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -39,6 +39,7 @@
 #include <linux/net_tstamp.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
+#include <linux/if.h>
 #include <linux/if_vlan.h>
 #include <linux/pci.h>
 #include <linux/pci-aspm.h>
@@ -1973,6 +1974,8 @@
 		netdev->features |= NETIF_F_SCTP_CSUM;
 	}
 
+	netdev->priv_flags |= IFF_UNICAST_FLT;
+
 	adapter->en_mng_pt = igb_enable_mng_pass_thru(hw);
 
 	/* before reading the NVM, reset the controller to put the device in a