x86: enable "make ARCH=x86"

After unification of the Kconfig files and
introducing K64BIT support in kconfig
it required only trivial changes to enable
"make ARCH=x86".

With this patch you can build for x86_64 in several ways:
1) make ARCH=x86_64
2) make ARCH=x86 K64BIT=y
3) make ARCH=x86 menuconfig
   => select 64-bit

Likewise for i386 with the addition that
i386 is default is you say ARCH=x86.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 34517bf..1eb5997 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1,13 +1,25 @@
 # x86 configuration
+mainmenu "Linux Kernel Configuration for x86"
+
+# Select 32 or 64 bit
+config 64BIT
+	bool "64-bit kernel"
+	default n
+	help
+	  Say yes to build a 64-bit kernel - formerly known as x86_64
+	  Say no to build a 32-bit kernel - formerly known as i386
+
+config X86_32
+	def_bool !64BIT
+
+config X86_64
+	def_bool 64BIT
 
 ### Arch settings
 config X86
 	bool
 	default y
 
-config 64BIT
-	def_bool X86_64
-
 config GENERIC_TIME
 	bool
 	default y