* Energymicro efm32 UART

Required properties:
- compatible : Should be "efm32,uart"
- reg : Address and length of the register set
- interrupts : Should contain uart interrupt

Optional properties:
- location : Decides the location of the USART I/O pins.
  Allowed range : [0 .. 5]
  Default: 0

Example:

uart@0x4000c400 {
	compatible = "efm32,uart";
	reg = <0x4000c400 0x400>;
	interrupts = <15>;
	location = <0>;
};