soc : mec1501 : Deep and light sleep example

Created MEC1501 deep and light sleep example for MCHP MEC1501.
Modifications were made to SoC, board, timer, and hello world
sample program. Power management split into SoC power
implementing the interface and device power for device specific
logic.

Signed-off-by: Scott Worley <scott.worley@microchip.com>