batman-adv: bla: fix type misuse for backbone_gw hash indexing

It seems that due to a copy & paste error the void pointer
in batadv_choose_backbone_gw() is cast to the wrong type.

Fixing this by using "struct batadv_bla_backbone_gw" instead of "struct
batadv_bla_claim" which better matches the caller's side.

For now it seems that we were lucky because the two structs both have
their orig/vid and addr/vid in the beginning. However I stumbled over
this issue when I was trying to add some debug variables in front of
"orig" in batadv_backbone_gw, which caused hash lookups to fail.

Fixes: 07568d03 ("batman-adv: don't rely on positions in struct for hashing")
Signed-off-by: Linus Lüssing <ll@simonwunderlich.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

net/batman-adv/bridge_loop_avoidance.c

@@ -83,11 +83,12 @@ static inline u32 batadv_choose_claim(const void *data, u32 size)
  */
 static inline u32 batadv_choose_backbone_gw(const void *data, u32 size)
 {
-	const struct batadv_bla_claim *claim = (struct batadv_bla_claim *)data;
+	const struct batadv_bla_backbone_gw *gw;
 	u32 hash = 0;
 
-	hash = jhash(&claim->addr, sizeof(claim->addr), hash);
-	hash = jhash(&claim->vid, sizeof(claim->vid), hash);
+	gw = (struct batadv_bla_backbone_gw *)data;
+	hash = jhash(&gw->orig, sizeof(gw->orig), hash);
+	hash = jhash(&gw->vid, sizeof(gw->vid), hash);
 
 	return hash % size;
 }