Power test example, running demonstration of energy modes.

This example project use EFM32 CMSIS and the emlib peripheral library
to demonstrate the use of the various Energy Modes available on the
EFM32 Gecko devices. When running this example, the EnergyAware Profiler tool
in Simplicity Studio can be used to show the power consumption of each 
energy mode.

Board:  Silicon Labs EFM32_Gxxx_DK Development Kit
Device: EFM32G890F128 or EFM32G290F128
