Add x64 support to src/arch/x86/Kconfig

Change-Id: I81f6d8a21ea0d8218f5a4aab2feb39be32f88e01
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Signed-off-by: Scott Duplichan <scott@notabs.org>
Reviewed-on: http://review.coreboot.org/8692
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/arch/x86/Kconfig

@@ -18,6 +18,8 @@ config ARCH_X86
 	default n
 	select PCI
 
+# stage selectors for x86
+
 config ARCH_BOOTBLOCK_X86_32
 	bool
 	default n
@@ -35,6 +37,25 @@ config ARCH_RAMSTAGE_X86_32
 	bool
 	default n
 
+# stage selectors for x64
+
+config ARCH_BOOTBLOCK_X86_64
+	bool
+	default n
+	select ARCH_X86
+
+config ARCH_VERSTAGE_X86_64
+	bool
+	default n
+
+config ARCH_ROMSTAGE_X86_64
+	bool
+	default n
+
+config ARCH_RAMSTAGE_X86_64
+	bool
+	default n
+
 # This is an SMP option. It relates to starting up APs.
 # It is usually set in mainboard/*/Kconfig.
 # TODO: Improve description.