p54spi: Add missing spin_lock_init

The tx_lock is not initialized properly. Add spin_lock_init().
Signed-off-by: Michael Buesch <m@bues.ch>
Cc: <stable@vger.kernel.org>
Acked-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/p54/p54spi.c

@@ -656,6 +656,7 @@ static int __devinit p54spi_probe(struct spi_device *spi)
 	init_completion(&priv->fw_comp);
 	INIT_LIST_HEAD(&priv->tx_pending);
 	mutex_init(&priv->mutex);
+	spin_lock_init(&priv->tx_lock);
 	SET_IEEE80211_DEV(hw, &spi->dev);
 	priv->common.open = p54spi_op_start;
 	priv->common.stop = p54spi_op_stop;