arm64: dts: freescale: imx93-phyboard-nash: Add pwm-fan overlay

arm64: dts: freescale: imx93-phyboard-nash: Add pwm-fan overlay

Add overlay to support PWM fan on the phyBOARD-Nash-i.MX93 board. Fan
can be connected to the FAN (X48) connector on the board and will be
controlled according to the following CPU temperature trips table:

 - bellow 50 degrees - fan is off (<1% duty cycle)
 - between 50 and 58 degrees - low fan speed (~35% duty cycle)
 - between 58 and 65 degrees - fan medium speed (~60% duty cycle)
 - above 65 degrees - fan at full speed (>99% duty cycle)

The output frequency of PWM signal is set to 25 kHz.

Signed-off-by: Primoz Fiser <primoz.fiser@norik.com>
Reviewed-by: Alberto Merciai <alb3rt0.m3rciai@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>