Freescale i.MX TPM PWM controller

Required properties:
- compatible : Should be "fsl,imx7ulp-pwm".
- reg: Physical base address and length of the controller's registers.
- #pwm-cells: Should be 3. See pwm.yaml in this directory for a description of the cells format.
- clocks : The clock provided by the SoC to drive the PWM.
- interrupts: The interrupt for the PWM controller.

Note: The TPM counter and period counter are shared between multiple channels, so all channels
should use same period setting.

Example:

tpm4: pwm@40250000 {
	compatible = "fsl,imx7ulp-pwm";
	reg = <0x40250000 0x1000>;
	assigned-clocks = <&pcc2 IMX7ULP_CLK_LPTPM4>;
	assigned-clock-parents = <&scg1 IMX7ULP_CLK_SOSC_BUS_CLK>;
	clocks = <&pcc2 IMX7ULP_CLK_LPTPM4>;
	#pwm-cells = <3>;
};