batman-adv: Prefix gateway-client non-static functions with batadv_

batman-adv can be compiled as part of the kernel instead of an module. In that
case the linker will see all non-static symbols of batman-adv and all other
non-static symbols of the kernel. This could lead to symbol collisions. A
prefix for the batman-adv symbols that defines their private namespace avoids
such a problem.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index 3e1bb7a..8fe70b4 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -149,7 +149,7 @@
 
 	vis_quit(bat_priv);
 
-	gw_node_purge(bat_priv);
+	batadv_gw_node_purge(bat_priv);
 	originator_free(bat_priv);
 
 	tt_free(bat_priv);