net: ti: icssg-prueth: Fix signedness bug in prueth_init_rx_chns()

The rx_chn->irq[] array is unsigned int but it should be signed for the
error handling to work. Also if k3_udma_glue_rx_get_irq() returns zero
then we should return -ENXIO instead of success.

Fixes: 128d5874c082 ("net: ti: icssg-prueth: Add ICSSG ethernet driver")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: Roger Quadros <[e-mail]>
Reviewed-by: MD Danish Anwar <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 		if (!i)
 			fdqring_id = k3_udma_glue_rx_flow_get_fdq_id(rx_chn->rx_chn,
 								     i);
-		rx_chn->irq[i] = k3_udma_glue_rx_get_irq(rx_chn->rx_chn, i);
-		if (rx_chn->irq[i] <= 0) {
-			ret = rx_chn->irq[i];
+		ret = k3_udma_glue_rx_get_irq(rx_chn->rx_chn, i);
+		if (ret <= 0) {
+			if (!ret)
+				ret = -ENXIO;
 			netdev_err(ndev, "Failed to get rx dma irq");
 			goto fail;
 		}
+		rx_chn->irq[i] = ret;
 	}
 
 	return 0;