PCI: Only build PCI syscalls on architectures that want them

The PCI syscalls are built on every architecture except X86, but only
a few have ever hooked them up.  Use a new Kconfig symbol to save a
couple of kB on the architectures that have never used the syscalls.
Tested on x86 and ia64 only.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5eaeafd..6beee32 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -698,8 +698,10 @@
 	  infrastructure code to support PCI bus devices.
 
 config PCI_DOMAINS
-	bool
-	default PCI
+	def_bool PCI
+
+config PCI_SYSCALL
+	def_bool PCI
 
 config PCI_QSPAN
 	bool "QSpan PCI"