pseq: Add power state/power good to System class

Add the following to the power sequencer System class:
* Power state and power good data members
* Methods to get power state and power good values
*

pseq: Add power state/power good to System class

Add the following to the power sequencer System class:
* Power state and power good data members
* Methods to get power state and power good values
* Method to set the power state to power the system on/off
* Method to monitor the system and update the power good value

Tested:
* Ran automated tests
* Tested new methods in simulation:
* Verified getPowerState() returned correct value when system on/off
* Verified setPowerState() set the power control GPIO correctly
* Verified getPowerGood() returned correct value when system on/off
* Verified monitor() obtained the current power good value when system
on/off

Change-Id: Ie7f01bccac330240a3d8173805d77badb5f5b3c8
Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>

show more ...