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
EFM32LG990F256. 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 EFM32LG-DK3650 Development Kit
Device: EFM32LG990F256
