rt2x00: Fix incorrect usage of CONFIG_RT2X00_LIB_USB

In device removal routine, usage of "#ifdef CONFIG_RT2X00_LIB_USB"
will not cover the case when it is configured as module. This will
omit the entire if-block which does cleanup of URBs and cancellation
of pending work. Changing the #ifdef to #if IS_ENABLED() to fix it.
Signed-off-by: Vishal Thanki <vishalthanki@gmail.com>
Acked-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2x00dev.c

@@ -1439,7 +1439,7 @@ void rt2x00lib_remove_dev(struct rt2x00_dev *rt2x00dev)
 	cancel_work_sync(&rt2x00dev->intf_work);
 	cancel_delayed_work_sync(&rt2x00dev->autowakeup_work);
 	cancel_work_sync(&rt2x00dev->sleep_work);
-#ifdef CONFIG_RT2X00_LIB_USB
+#if IS_ENABLED(CONFIG_RT2X00_LIB_USB)
 	if (rt2x00_is_usb(rt2x00dev)) {
 		usb_kill_anchored_urbs(rt2x00dev->anchor);
 		hrtimer_cancel(&rt2x00dev->txstatus_timer);