x86: arch/x86/Kconfig.cpu unification

Move all CPU definitions to Kconfig.cpu
Always define X86_MINIMUM_CPU_FAMILY and do the
obvious code cleanup in boot/cpucheck.c

Comments from: Adrian Bunk <bunk@kernel.org> incorporated.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Brian Gerst <bgerst@didntduck.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>

arch/x86/boot/cpucheck.c

@@ -42,13 +42,7 @@ static struct cpu_features cpu;
 static u32 cpu_vendor[3];
 static u32 err_flags[NCAPINTS];
 
-#ifdef CONFIG_X86_64
-static const int req_level = 64;
-#elif defined(CONFIG_X86_MINIMUM_CPU_FAMILY)
 static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY;
-#else
-static const int req_level = 3;
-#endif
 
 static const u32 req_flags[NCAPINTS] =
 {