power_mgmt: Add Deep Sleep support in sample PM app

Added changes to enhance device suspend/resume involving
core devices used by OS and app. Updated with Deep Sleep
power policy usage example. Moved the arch/soc dependent
code to soc/arch dependent areas in Zephyr in a separate
patch.  This app now uses api that abstracts the soc/arch
details in handling power states.

Jira: ZEP-511
Change-Id: I3b4eb0be973027dbf9bd046e16836f7863eee46e
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>