b43: Eliminate compilation warning in b43_op_set_key

A recent pull from wireless testing generates the following warning:

   CC [M]  drivers/net/wireless/b43/main.o
 drivers/net/wireless/b43/main.c: In function ‘b43_op_set_key’:
 drivers/net/wireless/b43/main.c:3636: warning: pointer type mismatch
 in conditional expression

This fix was suggested by Johannes Berg <johannes@sipsolutions.net>.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/main.c

@@ -3484,6 +3484,9 @@ static int b43_op_set_key(struct ieee80211_hw *hw, enum set_key_cmd cmd,
 	u8 algorithm;
 	u8 index;
 	int err;
+#if B43_DEBUG
+	static const u8 bcast_addr[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+#endif
 
 	if (modparam_nohwcrypt)
 		return -ENOSPC; /* User disabled HW-crypto */
@@ -3582,7 +3585,7 @@ out_unlock:
 		b43dbg(wl, "%s hardware based encryption for keyidx: %d, "
 		       "mac: %pM\n",
 		       cmd == SET_KEY ? "Using" : "Disabling", key->keyidx,
-		       sta ? sta->addr : "<group key>");
+		       sta ? sta->addr : bcast_addr);
 		b43_dump_keymemory(dev);
 	}
 	write_unlock(&wl->tx_lock);