ata: sata_dwc_460ex: Check !irq instead of irq == NO_IRQ

NO_IRQ is a relic from the old days. It is not used anymore in core
functions. By the way, function irq_of_parse_and_map() returns value 0
on error.

In some drivers, NO_IRQ is erroneously used to check the return of
irq_of_parse_and_map().

It is not a real bug today because the only architectures using the
drivers being fixed by this patch define NO_IRQ as 0, but there are
architectures which define NO_IRQ as -1. If one day those
architectures start using the non fixed drivers, there will be a
problem.

Long time ago Linus advocated for not using NO_IRQ, see
https://lkml.org/lkml/2005/11/21/221 . He re-iterated the same view
recently in https://lkml.org/lkml/2022/10/12/622

So test !irq instead of tesing irq == NO_IRQ.

And remove the fallback definition of NO_IRQ at the top of the file.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/sata_dwc_460ex.c

@@ -42,10 +42,6 @@
 #define sata_dwc_writel(a, v)	writel_relaxed(v, a)
 #define sata_dwc_readl(a)	readl_relaxed(a)
 
-#ifndef NO_IRQ
-#define NO_IRQ		0
-#endif
-
 #define AHB_DMA_BRST_DFLT	64	/* 16 data items burst length */
 
 enum {
@@ -242,7 +238,7 @@ static int sata_dwc_dma_init_old(struct platform_device *pdev,
 
 	/* Get SATA DMA interrupt number */
 	hsdev->dma->irq = irq_of_parse_and_map(np, 1);
-	if (hsdev->dma->irq == NO_IRQ) {
+	if (!hsdev->dma->irq) {
 		dev_err(dev, "no SATA DMA irq\n");
 		return -ENODEV;
 	}
@@ -1178,7 +1174,7 @@ static int sata_dwc_probe(struct platform_device *ofdev)
 
 	/* Get SATA interrupt number */
 	irq = irq_of_parse_and_map(np, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		dev_err(dev, "no SATA DMA irq\n");
 		return -ENODEV;
 	}