b43: fix build error if !CONFIG_B43_LEDS

Fix the following build error when CONFIG_B43_LEDS is not selected:

drivers/net/wireless/b43/main.c: In function 'b43_remove':
drivers/net/wireless/b43/main.c:4990: error: 'struct b43_leds' has no member named 'stop'
drivers/net/wireless/b43/main.c:4991: error: 'struct b43_leds' has no member named 'work'
make[4]: *** [drivers/net/wireless/b43/main.o] Error 1

Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/main.c

@@ -4987,8 +4987,7 @@ static void b43_remove(struct ssb_device *dev)
 		 * might have modified it. Restoring is important, so the networking
 		 * stack can properly free resources. */
 		wl->hw->queues = wl->mac80211_initially_registered_queues;
-		wl->leds.stop = 1;
-		cancel_work_sync(&wl->leds.work);
+		b43_leds_stop(wldev);
 		ieee80211_unregister_hw(wl->hw);
 	}