b43legacy: Fix unload oops if firmware is not available

commit 45202866 upstream.

The asyncronous firmware load uses a completion struct to hold firmware
processing until the user-space routines are up and running. There is.
however, a problem in that the waiter is nevered canceled during teardown.
As a result, unloading the driver when firmware is not available causes an oops.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/wireless/b43legacy/main.c

@@ -3915,6 +3915,7 @@ static void b43legacy_remove(struct ssb_device *dev)
 	 * as the ieee80211 unreg will destroy the workqueue. */
 	cancel_work_sync(&wldev->restart_work);
 	cancel_work_sync(&wl->firmware_load);
+	complete(&wldev->fw_load_complete);
 
 	B43legacy_WARN_ON(!wl);
 	if (!wldev->fw.ucode)