batman-adv: Use bool as return type for boolean functions

It is easier to understand that the returned value of a specific function
doesn't have to be 0 when the functions was successful when the actual
return type is bool. This is especially true when all surrounding functions
with return type int use negative values to return the error code.

Reported-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
diff --git a/net/batman-adv/hash.h b/net/batman-adv/hash.h
index 9bb57b8..cbbf870 100644
--- a/net/batman-adv/hash.h
+++ b/net/batman-adv/hash.h
@@ -32,10 +32,10 @@
 /* callback to a compare function.  should compare 2 element datas for their
  * keys
  *
- * Return: 0 if same and not 0 if not same
+ * Return: true if same and false if not same
  */
-typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *,
-					  const void *);
+typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
+					   const void *);
 
 /* the hashfunction
  *