tty: serial: imx: correct dma cookie status

Correct to check the right rx dma cookie status in spit of it
works because only one cookie is running in the current sdma.
But it will not once sdma driver support multi cookies
running based on virt-dma.
Signed-off-by: NRobin Gong <yibin.gong@nxp.com>
Reviewed-by: NSascha Hauer <s.hauer@pengutronix.de>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: NLucas Stach <l.stach@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -1052,7 +1052,7 @@ static void imx_uart_dma_rx_callback(void *data)
 	unsigned int r_bytes;
 	unsigned int bd_size;
 
-	status = dmaengine_tx_status(chan, (dma_cookie_t)0, &state);
+	status = dmaengine_tx_status(chan, sport->rx_cookie, &state);
 
 	if (status == DMA_ERROR) {
 		imx_uart_clear_rx_errors(sport);