powerpc/chrp/pci: Make some functions static

These functions can all be static, make it so. Fix warnings treated as
errors with W=1:

arch/powerpc/platforms/chrp/pci.c:34:5: error: no previous prototype for ‘gg2_read_config’ [-Werror=missing-prototypes]
arch/powerpc/platforms/chrp/pci.c:61:5: error: no previous prototype for ‘gg2_write_config’ [-Werror=missing-prototypes]
arch/powerpc/platforms/chrp/pci.c:97:5: error: no previous prototype for ‘rtas_read_config’ [-Werror=missing-prototypes]
arch/powerpc/platforms/chrp/pci.c:112:5: error: no previous prototype for ‘rtas_write_config’ [-Werror=missing-prototypes]

Signed-off-by: Mathieu Malaterre <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/platforms/chrp/pci.c

···
  * limit the bus number to 3 bits
  */
 
-int gg2_read_config(struct pci_bus *bus, unsigned int devfn, int off,
+static int gg2_read_config(struct pci_bus *bus, unsigned int devfn, int off,
 			   int len, u32 *val)
 {
 	volatile void __iomem *cfg_data;
···
 	return PCIBIOS_SUCCESSFUL;
 }
 
-int gg2_write_config(struct pci_bus *bus, unsigned int devfn, int off,
+static int gg2_write_config(struct pci_bus *bus, unsigned int devfn, int off,
 			    int len, u32 val)
 {
 	volatile void __iomem *cfg_data;
···
 /*
  * Access functions for PCI config space using RTAS calls.
  */
-int rtas_read_config(struct pci_bus *bus, unsigned int devfn, int offset,
-		     int len, u32 *val)
+static int rtas_read_config(struct pci_bus *bus, unsigned int devfn, int offset,
+			    int len, u32 *val)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
 	unsigned long addr = (offset & 0xff) | ((devfn & 0xff) << 8)
···
 	return rval? PCIBIOS_DEVICE_NOT_FOUND: PCIBIOS_SUCCESSFUL;
 }
 
-int rtas_write_config(struct pci_bus *bus, unsigned int devfn, int offset,
-		      int len, u32 val)
+static int rtas_write_config(struct pci_bus *bus, unsigned int devfn, int offset,
+			     int len, u32 val)
 {
 	struct pci_controller *hose = pci_bus_to_host(bus);
 	unsigned long addr = (offset & 0xff) | ((devfn & 0xff) << 8)