Enable runtime pm support for xenon controller, which uses 50ms
auto runtime suspend by default.
Reimplement system standby based on runtime pm API.
Introduce restore_needed to restore the Xenon specific registers
when resume.
Signed-off-by: Zhoujie Wu <zjwu@marvell.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>