x86: add memory hotremove config option

Impact: enable CONFIG_MEMORY_HOTREMOVE feature on x86. (default-off)

Memory hotremove functionality can currently be configured into
the ia64, powerpc, and s390 kernels.

This patch makes it possible to configure the memory hotremove
functionality into the x86 kernel as well.
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NGary Hade <garyhade@us.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/Kconfig

@@ -1492,6 +1492,10 @@ config ARCH_ENABLE_MEMORY_HOTPLUG
 	def_bool y
 	depends on X86_64 || (X86_32 && HIGHMEM)
 
+config ARCH_ENABLE_MEMORY_HOTREMOVE
+	def_bool y
+	depends on MEMORY_HOTPLUG
+
 config HAVE_ARCH_EARLY_PFN_TO_NID
 	def_bool X86_64
 	depends on NUMA