davinci: cpuidle - move code to prevent forward declaration

The patch is mindless, it just moves the idle function below in the file
in order to prevent forward declaration in the next patch.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Len Brown <len.brown@intel.com>