net: bridge: constify variables in the replay helpers

Some of the arguments and local variables for the newly added switchdev
replay helpers can be const, so let's make them so.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index 3dafb61..1d80f34 100644
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -639,9 +639,9 @@ int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
 	return 0;
 }
 
-clock_t br_get_ageing_time(struct net_device *br_dev)
+clock_t br_get_ageing_time(const struct net_device *br_dev)
 {
-	struct net_bridge *br;
+	const struct net_bridge *br;
 
 	if (!netif_is_bridge_master(br_dev))
 		return 0;