batman-adv: make batadv_test_bit() return 0 or 1 only

On some architectures test_bit() can return other values than 0 or 1:

With a generic x86 OpenWrt image in a kvm setup (batadv_)test_bit()
frequently returns -1 for me, leading to batadv_iv_ogm_update_seqnos()
wrongly signaling a protected seqno window.

This patch tries to fix this issue by making batadv_test_bit() return 0
or 1 only.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Acked-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/batman-adv/bitarray.h

@@ -20,8 +20,8 @@
 #ifndef _NET_BATMAN_ADV_BITARRAY_H_
 #define _NET_BATMAN_ADV_BITARRAY_H_
 
-/* returns true if the corresponding bit in the given seq_bits indicates true
- * and curr_seqno is within range of last_seqno
+/* Returns 1 if the corresponding bit in the given seq_bits indicates true
+ * and curr_seqno is within range of last_seqno. Otherwise returns 0.
  */
 static inline int batadv_test_bit(const unsigned long *seq_bits,
 				  uint32_t last_seqno, uint32_t curr_seqno)
@@ -32,7 +32,7 @@ static inline int batadv_test_bit(const unsigned long *seq_bits,
 	if (diff < 0 || diff >= BATADV_TQ_LOCAL_WINDOW_SIZE)
 		return 0;
 	else
-		return  test_bit(diff, seq_bits);
+		return test_bit(diff, seq_bits) != 0;
 }
 
 /* turn corresponding bit on, so we can remember that we got the packet */