p54spi: Remove FIXME in op_stop

Don't use the interruptible variant of mutex_lock(). It doesn't really
need to be interruptible. This avoids nasty error handling.
Signed-off-by: Michael Buesch <m@bues.ch>
Acked-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54spi.c

@@ -581,11 +581,7 @@ static void p54spi_op_stop(struct ieee80211_hw *dev)
 	struct p54s_priv *priv = dev->priv;
 	unsigned long flags;
 
-	if (mutex_lock_interruptible(&priv->mutex)) {
-		/* FIXME: how to handle this error? */
-		return;
-	}
-
+	mutex_lock(&priv->mutex);
 	WARN_ON(priv->fw_state != FW_STATE_READY);
 
 	cancel_work_sync(&priv->work);