ARM: S3C64XX: Add basic cpuidle driver

Add a very basic cpuidle driver for S3C64xx which merely drives the CPU
into IDLE mode. We could do this with pm_idle but the more modern idiom
is to use cpuidle and the intention is to go further and support STOP
and DEEP-STOP states in conjunction with the pm_domain framework.

The actual state entry code was lifted from Tomasz Figa's work on spica.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
diff --git a/arch/arm/mach-s3c64xx/Makefile b/arch/arm/mach-s3c64xx/Makefile
index 1822ac2..610fe28 100644
--- a/arch/arm/mach-s3c64xx/Makefile
+++ b/arch/arm/mach-s3c64xx/Makefile
@@ -22,6 +22,7 @@
 # PM
 
 obj-$(CONFIG_PM)		+= pm.o irq-pm.o sleep.o
+obj-$(CONFIG_CPU_IDLE)		+= cpuidle.o
 
 # DMA support