STMicroelectronics STM32 Low-Power Timer Trigger

STM32 Low-Power Timer provides trigger source (LPTIM output) that can be used
by STM32 internal ADC and/or DAC.

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-trigger".
- reg:			Identify trigger hardware block. Must be 0, 1 or 2
			respectively for lptimer1, lptimer2 or lptimer3
			trigger output.

Example:
	timer@40002400 {
		compatible = "st,stm32-lptimer";
		...
		trigger@0 {
			compatible = "st,stm32-lptimer-trigger";
			reg = <0>;
		};
	};
