mlxsw: spectrum_router: Don't destroy RIF if L3 slave

We usually destroy the netdev's router interface (RIF) when the last IP
address is removed from it.

However, we shouldn't do that if it's enslaved to an L3 master device.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -41,6 +41,7 @@
 #include <linux/in6.h>
 #include <linux/notifier.h>
 #include <linux/inetdevice.h>
+#include <linux/netdevice.h>
 #include <net/netevent.h>
 #include <net/neighbour.h>
 #include <net/arp.h>
@@ -2660,7 +2661,7 @@ static bool mlxsw_sp_rif_should_config(struct mlxsw_sp_rif *r,
 			return true;
 		return false;
 	case NETDEV_DOWN:
-		if (r && !in_dev->ifa_list)
+		if (r && !in_dev->ifa_list && !netif_is_l3_slave(r->dev))
 			return true;
 		/* It is possible we already removed the RIF ourselves
 		 * if it was assigned to a netdev that is now a bridge