net: hsr: hsr_slave: Fix the promiscuous mode in offload mode

commit e748d0f ("net: hsr: Disable promiscuous mode in
offload mode") disables promiscuous mode of slave devices
while creating an HSR interface. But while deleting the
HSR interface, it does not take care of it. It decreases the
promiscuous mode count, which eventually enables promiscuous
mode on the slave devices when creating HSR interface again.

Fix this by not decrementing the promiscuous mode count while
deleting the HSR interface when offload is enabled.

Fixes: e748d0f ("net: hsr: Disable promiscuous mode in offload mode")
Signed-off-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240322100447.27615-1-r-gunasekaran@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Ravi Gunasekaran

net/hsr/hsr_slave.c

@@ -220,7 +220,8 @@ void hsr_del_port(struct hsr_port *port)
 		netdev_update_features(master->dev);
 		dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));
 		netdev_rx_handler_unregister(port->dev);
-		dev_set_promiscuity(port->dev, -1);
+		if (!port->hsr->fwd_offloaded)
+			dev_set_promiscuity(port->dev, -1);
 		netdev_upper_dev_unlink(port->dev, master->dev);
 	}