net: Move netif_index_is_l3_master to l3mdev.h

Change CONFIG dependency to CONFIG_NET_L3_MASTER_DEV as well.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index e382c77..87cee05 100644
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -81,6 +81,25 @@
 	return NULL;
 }
 
+static inline bool netif_index_is_l3_master(struct net *net, int ifindex)
+{
+	struct net_device *dev;
+	bool rc = false;
+
+	if (ifindex == 0)
+		return false;
+
+	rcu_read_lock();
+
+	dev = dev_get_by_index_rcu(net, ifindex);
+	if (dev)
+		rc = netif_is_l3_master(dev);
+
+	rcu_read_unlock();
+
+	return rc;
+}
+
 #else
 
 static inline int l3mdev_master_ifindex_rcu(struct net_device *dev)
@@ -120,6 +139,11 @@
 	return NULL;
 }
 
+static inline bool netif_index_is_l3_master(struct net *net, int ifindex)
+{
+	return false;
+}
+
 #endif
 
 #endif /* _NET_L3MDEV_H_ */