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/ia64/Kconfig b/arch/ia64/Kconfig
index de1bff6..db9ddff 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -520,8 +520,10 @@
 	  here unless you are using a simulator without PCI support.
 
 config PCI_DOMAINS
-	bool
-	default PCI
+	def_bool PCI
+
+config PCI_SYSCALL
+	def_bool PCI
 
 source "drivers/pci/pcie/Kconfig"