[ARM SMP] Add hotplug CPU infrastructure

This patch adds the infrastructure to support hotplug CPU on ARM
platforms.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dc6d834..6b12d71 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -349,6 +349,13 @@
 	depends on SMP
 	default "4"
 
+config HOTPLUG_CPU
+	bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
+	depends on SMP && HOTPLUG && EXPERIMENTAL
+	help
+	  Say Y here to experiment with turning CPUs off and on.  CPUs
+	  can be controlled through /sys/devices/system/cpu.
+
 config PREEMPT
 	bool "Preemptible Kernel (EXPERIMENTAL)"
 	depends on EXPERIMENTAL