x86/PCI: Define to_pci_sysdata() even when !CONFIG_PCI

Recently, the to_pci_sysdata() helper was added inside the CONFIG_PCI
guard, but it is used inside a CONFIG_NUMA guard, which does not require
CONFIG_PCI.  This breaks builds on !CONFIG_PCI machines.  Make
to_pci_sysdata() available in all configurations.

Fixes: aad6aa0 ("x86/PCI: Add to_pci_sysdata() helper")
Link: https://lore.kernel.org/r/[email protected]
Reported-by: Randy Dunlap <[email protected]>
Signed-off-by: Jason A. Donenfeld <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Acked-by: Randy Dunlap <[email protected]>	# build-tested

Author: zx2c4

arch/x86/include/asm/pci.h

@@ -33,13 +33,13 @@ extern int pci_routeirq;
 extern int noioapicquirk;
 extern int noioapicreroute;
 
-#ifdef CONFIG_PCI
-
 static inline struct pci_sysdata *to_pci_sysdata(const struct pci_bus *bus)
 {
 	return bus->sysdata;
 }
 
+#ifdef CONFIG_PCI
+
 #ifdef CONFIG_PCI_DOMAINS
 static inline int pci_domain_nr(struct pci_bus *bus)
 {