net: add netif_is_team_master helper

Similar to other helpers, caller can use this to find out if device is
team master.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 651d35e..d2f3ee8 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -2054,6 +2054,7 @@
 	dev->flags |= IFF_MULTICAST;
 	dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
 	dev->priv_flags |= IFF_NO_QUEUE;
+	dev->priv_flags |= IFF_TEAM;
 
 	/*
 	 * Indicate we support unicast address filtering. That way core won't