STMicroelectronics STM32 Low-Power Timer quadrature encoder and counter

STM32 Low-Power Timer provides several counter modes. It can be used as:
- quadrature encoder to detect angular position and direction of rotary
  elements, from IN1 and IN2 input signals.
- simple counter from IN1 input signal.

Must be a sub-node of an STM32 Low-Power Timer device tree node.
See ../mfd/stm32-lptimer.txt for details about the parent node.

Required properties:
- compatible:		Must be "st,stm32-lptimer-counter".
- pinctrl-names: 	Set to "default". An additional "sleep" state can be
			defined to set pins in sleep state.
- pinctrl-n: 		List of phandles pointing to pin configuration nodes,
			to set IN1/IN2 pins in mode of operation for Low-Power
			Timer input on external pin.

Example:
	timer@40002400 {
		compatible = "st,stm32-lptimer";
		...
		counter {
			compatible = "st,stm32-lptimer-counter";
			pinctrl-names = "default", "sleep";
			pinctrl-0 = <&lptim1_in_pins>;
			pinctrl-1 = <&lptim1_sleep_in_pins>;
		};
	};
