APM idle: register apm_cpu_idle via cpuidle

Update APM to register its local idle routine with cpuidle.

This allows us to stop exporting pm_idle to modules on x86.

The Kconfig sub-option, APM_CPU_IDLE, now depends on on CPU_IDLE.

Compile-tested only.

Signed-off-by: Len Brown <len.brown@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Jiri Kosina <jkosina@suse.cz>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 225543b..1b63586 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1912,6 +1912,7 @@
 	  this feature.
 
 config APM_CPU_IDLE
+	depends on CPU_IDLE
 	bool "Make CPU Idle calls when idle"
 	---help---
 	  Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.