x86: replace CONFIG_X86_SMP with CONFIG_SMP

The x86/Voyager subarch used to have this distinction between
 'x86 SMP support' and 'Voyager SMP support':

 config X86_SMP
	bool
	depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)

This is a pointless distinction - Voyager can (and already does) use
smp_ops to implement various SMP quirks it has - and it can be extended
more to cover all the specialities of Voyager.

So remove this complication in the Kconfig space.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig.debug

@@ -83,7 +83,7 @@ config DEBUG_PAGEALLOC
 config DEBUG_PER_CPU_MAPS
 	bool "Debug access to per_cpu maps"
 	depends on DEBUG_KERNEL
-	depends on X86_SMP
+	depends on SMP
 	default n
 	help
 	  Say Y to verify that the per_cpu map being accessed has