PCI: consolidate the PCI_DOMAINS and PCI_DOMAINS_GENERIC config options

Move the definitions to drivers/pci and let the architectures select
them.  Two small differences to before: PCI_DOMAINS_GENERIC now selects
PCI_DOMAINS, cutting down the churn for modern architectures.  As the
only architectured arm did previously also offer PCI_DOMAINS as a user
visible choice in addition to selecting it from the relevant configs,
this is gone now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index ef6ea81..2bf98e5 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -7,6 +7,7 @@
 	select ARCH_NO_PREEMPT
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select FORCE_PCI if !ALPHA_JENSEN
+	select PCI_DOMAINS if PCI
 	select HAVE_AOUT
 	select HAVE_IDE
 	select HAVE_OPROFILE
@@ -321,10 +322,6 @@
 	bool
 	default y
 
-config PCI_DOMAINS
-	bool
-	default y
-
 config PCI_SYSCALL
 	def_bool PCI