dmaengine: ti: k3-udma-glue: clean up k3_udma_glue_tx_get_irq() return

The k3_udma_glue_tx_get_irq() function currently returns negative error
codes on error, zero on error and positive values for success.  This
complicates life for the callers who need to propagate the error code.
Also GCC will not warn about unsigned comparisons when you check:

	if (unsigned_irq <= 0)

All the callers have been fixed now but let's just make this easy going
forward.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/dma/ti/k3-udma-glue.c

@@ -558,6 +558,9 @@ int k3_udma_glue_tx_get_irq(struct k3_udma_glue_tx_channel *tx_chn)
 		tx_chn->virq = k3_ringacc_get_ring_irq_num(tx_chn->ringtxcq);
 	}
 
+	if (!tx_chn->virq)
+		return -ENXIO;
+
 	return tx_chn->virq;
 }
 EXPORT_SYMBOL_GPL(k3_udma_glue_tx_get_irq);

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -1747,10 +1747,10 @@ static int am65_cpsw_nuss_init_tx_chns(struct am65_cpsw_common *common)
 		}
 
 		tx_chn->irq = k3_udma_glue_tx_get_irq(tx_chn->tx_chn);
-		if (tx_chn->irq <= 0) {
+		if (tx_chn->irq < 0) {
 			dev_err(dev, "Failed to get tx dma irq %d\n",
 				tx_chn->irq);
-			ret = tx_chn->irq ?: -ENXIO;
+			ret = tx_chn->irq;
 			goto err;
 		}
 

drivers/net/ethernet/ti/icssg/icssg_prueth.c

@@ -317,9 +317,7 @@ static int prueth_init_tx_chns(struct prueth_emac *emac)
 		}
 
 		ret = k3_udma_glue_tx_get_irq(tx_chn->tx_chn);
-		if (ret <= 0) {
-			if (!ret)
-				ret = -EINVAL;
+		if (ret < 0) {
 			netdev_err(ndev, "failed to get tx irq\n");
 			goto fail;
 		}