switchdev: change BUG_ON to WARN for attr set failure case

This particular BUG_ON condition was checking for attr set err in the
COMMIT phase, which isn't expected (it's a driver bug if PREPARE phase is
OK but COMMIT fails).  But BUG_ON() is too strong for this case, so change
to WARN().  BUG_ON() would be warranted if the system was corrupted beyond
repair, but this is not the case here.
Signed-off-by: NScott Feldman <sfeldma@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/switchdev/switchdev.c

@@ -184,7 +184,8 @@ int switchdev_port_attr_set(struct net_device *dev, struct switchdev_attr *attr)
 
 	attr->trans = SWITCHDEV_TRANS_COMMIT;
 	err = __switchdev_port_attr_set(dev, attr);
-	BUG_ON(err);
+	WARN(err, "%s: Commit of attribute (id=%d) failed.\n",
+	     dev->name, attr->id);
 
 	return err;
 }