National Instruments Ettus Research USRP E3x0 button driver

This module is part of the NI Ettus Research USRP E3x0 SDR.

This module provides a simple power button event via two interrupts.

Required properties:
- compatible: should be one of the following
  - "ettus,e3x0-button": For devices such as the NI Ettus Research USRP E3x0
- interrupts: should be one of the following
  - <0 30 1>, <0 31 1>: For devices such as the NI Ettus Research USRP E3x0
- interrupt-names: should be one of the following
  - "press", "release": For devices such as the NI Ettus Research USRP E3x0

Note: Interrupt numbers might vary depending on the FPGA configuration.

Example:
	button {
		compatible = "ettus,e3x0-button";
		interrupt-parent = <&intc>;
		interrupts = <0 30 1>, <0 31 1>;
		interrupt-names = "press", "release";
	}