dmaengine: at_hdmac: Return dma_cookie_status()'s ret code when txstate is NULL

txstate is an optional parameter used to get a struct with auxilary
transfer status information. When not provided the call to
device_tx_status() should return the status of the dma cookie. Return the
status of dma cookie when the txstate optional parameter is not provided.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-18-tudor.ambarus@microchip.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/at_hdmac.c

@@ -1461,14 +1461,8 @@ atc_tx_status(struct dma_chan *chan,
 	int bytes = 0;
 
 	ret = dma_cookie_status(chan, cookie, txstate);
-	if (ret == DMA_COMPLETE)
+	if (ret == DMA_COMPLETE || !txstate)
 		return ret;
-	/*
-	 * There's no point calculating the residue if there's
-	 * no txstate to store the value.
-	 */
-	if (!txstate)
-		return DMA_ERROR;
 
 	spin_lock_irqsave(&atchan->lock, flags);