tty/serial: at91: fix typo and indentation

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/atmel_serial.c

@@ -738,7 +738,11 @@ static void atmel_complete_tx_dma(void *arg)
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	/* Do we really need this? */
+	/*
+	 * xmit is a circular buffer so, if we have just send data from
+	 * xmit->tail to the end of xmit->buf, now we have to transmit the
+	 * remaining data from the beginning of xmit->buf to xmit->head.
+	 */
 	if (!uart_circ_empty(xmit))
 		tasklet_schedule(&atmel_port->tasklet);