PCI: Move of_irq_parse_and_map_pci() declaration under OF_IRQ

Since commit 4670d610 ("PCI: Move OF-related PCI functions into
PCI core"), sparc:allmodconfig fails to build with the following error.

  pcie-cadence-host.c:(.text+0x4c4): undefined reference to `of_irq_parse_and_map_pci'
  pcie-cadence-host.c:(.text+0x4c8): undefined reference to `of_irq_parse_and_map_pci'

of_irq_parse_and_map_pci() is now only available if OF_IRQ is enabled.
Make its declaration and its dummy function dependent on OF_IRQ to solve
the problem.

Fixes: 4670d610 ("PCI: Move OF-related PCI functions into PCI core")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>

include/linux/of_pci.h

@@ -13,7 +13,6 @@ struct device_node;
 struct device_node *of_pci_find_child_device(struct device_node *parent,
 					     unsigned int devfn);
 int of_pci_get_devfn(struct device_node *np);
-int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
 int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
 int of_get_pci_domain_nr(struct device_node *node);
 int of_pci_get_max_link_speed(struct device_node *node);
@@ -33,12 +32,6 @@ static inline int of_pci_get_devfn(struct device_node *np)
 	return -EINVAL;
 }
 
-static inline int
-of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
-{
-	return 0;
-}
-
 static inline int
 of_pci_parse_bus_range(struct device_node *node, struct resource *res)
 {
@@ -67,6 +60,16 @@ of_pci_get_max_link_speed(struct device_node *node)
 static inline void of_pci_check_probe_only(void) { }
 #endif
 
+#if IS_ENABLED(CONFIG_OF_IRQ)
+int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
+#else
+static inline int
+of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
+{
+	return 0;
+}
+#endif
+
 #if defined(CONFIG_OF_ADDRESS)
 int of_pci_get_host_bridge_resources(struct device_node *dev,
 			unsigned char busno, unsigned char bus_max,