* TWL4030's Keypad Controller device tree bindings

TWL4030's Keypad controller is used to interface a SoC with a matrix-type
keypad device. The keypad controller supports multiple row and column lines.
A key can be placed at each intersection of a unique row and a unique column.
The keypad controller can sense a key-press and key-release and report the
event using a interrupt to the cpu.

This binding is based on the matrix-keymap binding with the following
changes:

 * keypad,num-rows and keypad,num-columns are required.

Required SoC Specific Properties:
- compatible: should be one of the following
   - "ti,twl4030-keypad": For controllers compatible with twl4030 keypad
      controller.
- interrupt: should be one of the following
   - <1>: For controllers compatible with twl4030 keypad controller.

Example:
	twl_keypad: keypad {
		compatible = "ti,twl4030-keypad";
		interrupts = <1>;
		keypad,num-rows = <8>;
		keypad,num-columns = <8>;
	};
