mips: pci: Add ifdef around pci_proc_domain

Without these, there are multiple definitions of pci_proc_domain()
and pci_domain_nr() if linux/pci.h and asm/pci.h are included.

Add #ifdefs around them

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Reviewed-by: Markos Chandras <Markos.Chandras@imgtec.com>
Cc: Markos.Chandras@imgtec.com
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8670/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/pci.h

@@ -121,13 +121,15 @@ static inline void pci_dma_burst_advice(struct pci_dev *pdev,
 }
 #endif
 
+#ifdef CONFIG_PCI_DOMAINS
 #define pci_domain_nr(bus) ((struct pci_controller *)(bus)->sysdata)->index
 
 static inline int pci_proc_domain(struct pci_bus *bus)
 {
 	struct pci_controller *hose = bus->sysdata;
 	return hose->need_domain_info;
 }
+#endif /* CONFIG_PCI_DOMAINS */
 
 #endif /* __KERNEL__ */