x86/PCI: Disambiguate SiS85C503 PIRQ router code entities

In preparation to adding support for the SiS85C497 PIRQ router add `503' 
to the names of SiS85C503 PIRQ router code entities so that they clearly 
indicate which device they refer to.

Also restructure `sis_router_probe' such that new device IDs will be 
just new switch cases.

No functional change.
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2203301610000.22465@angie.orcam.me.uk

arch/x86/pci/irq.c

@@ -641,11 +641,12 @@ static int pirq_cyrix_set(struct pci_dev *router, struct pci_dev *dev, int pirq,
  *				bit 6-4 are probably unused, not like 5595
  */
 
-#define PIRQ_SIS_IRQ_MASK	0x0f
-#define PIRQ_SIS_IRQ_DISABLE	0x80
-#define PIRQ_SIS_USB_ENABLE	0x40
+#define PIRQ_SIS503_IRQ_MASK	0x0f
+#define PIRQ_SIS503_IRQ_DISABLE	0x80
+#define PIRQ_SIS503_USB_ENABLE	0x40
 
-static int pirq_sis_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
+static int pirq_sis503_get(struct pci_dev *router, struct pci_dev *dev,
+			   int pirq)
 {
 	u8 x;
 	int reg;
@@ -654,10 +655,11 @@ static int pirq_sis_get(struct pci_dev *router, struct pci_dev *dev, int pirq)
 	if (reg >= 0x01 && reg <= 0x04)
 		reg += 0x40;
 	pci_read_config_byte(router, reg, &x);
-	return (x & PIRQ_SIS_IRQ_DISABLE) ? 0 : (x & PIRQ_SIS_IRQ_MASK);
+	return (x & PIRQ_SIS503_IRQ_DISABLE) ? 0 : (x & PIRQ_SIS503_IRQ_MASK);
 }
 
-static int pirq_sis_set(struct pci_dev *router, struct pci_dev *dev, int pirq, int irq)
+static int pirq_sis503_set(struct pci_dev *router, struct pci_dev *dev,
+			   int pirq, int irq)
 {
 	u8 x;
 	int reg;
@@ -666,8 +668,8 @@ static int pirq_sis_set(struct pci_dev *router, struct pci_dev *dev, int pirq, i
 	if (reg >= 0x01 && reg <= 0x04)
 		reg += 0x40;
 	pci_read_config_byte(router, reg, &x);
-	x &= ~(PIRQ_SIS_IRQ_MASK | PIRQ_SIS_IRQ_DISABLE);
-	x |= irq ? irq: PIRQ_SIS_IRQ_DISABLE;
+	x &= ~(PIRQ_SIS503_IRQ_MASK | PIRQ_SIS503_IRQ_DISABLE);
+	x |= irq ? irq : PIRQ_SIS503_IRQ_DISABLE;
 	pci_write_config_byte(router, reg, x);
 	return 1;
 }
@@ -959,13 +961,14 @@ static __init int serverworks_router_probe(struct irq_router *r,
 
 static __init int sis_router_probe(struct irq_router *r, struct pci_dev *router, u16 device)
 {
-	if (device != PCI_DEVICE_ID_SI_503)
-		return 0;
-
-	r->name = "SIS";
-	r->get = pirq_sis_get;
-	r->set = pirq_sis_set;
+	switch (device) {
+	case PCI_DEVICE_ID_SI_503:
+		r->name = "SiS85C503";
+		r->get = pirq_sis503_get;
+		r->set = pirq_sis503_set;
 		return 1;
+	}
+	return 0;
 }
 
 static __init int cyrix_router_probe(struct irq_router *r, struct pci_dev *router, u16 device)