Update gpio-fan-overlay.dts (#2711)

/*

 * Overlay for the Raspberry Pi GPIO Fan @ BCM GPIO12.

 * References: 

 *	- https://www.raspberrypi.org/forums/viewtopic.php?f=107&p=1367135#p1365084

 *

 * Optional parameters:

 *	- "gpiopin"	- default GPIO12

 * 	- "temp"	- default 55000

 *	- "gpiopin"	- BCM number of the pin driving the fan, default 12 (GPIO12);

 * 	- "temp"	- CPU temperature at which fan is started in millicelsius, default 55000;

 *

 * Requires:

 *	- kernel configurations: CONFIG_SENSORS_GPIO_FAN=m and CONFIG_SENSORS_PWM_FAN=m;

 *	- kernel rebuid;

 *	- DC Fan connected to GPIO via a N-MOSFET (2N7002)

 *	- kernel configurations: CONFIG_SENSORS_GPIO_FAN=m;

 *	- kernel rebuild;

 *	- N-MOSFET connected to gpiopin, 2N7002-[https://en.wikipedia.org/wiki/2N7000];

 *	- DC Fan connected to N-MOSFET Drain terminal, a 12V fan is working fine and quite silently;

 *	  [https://www.tme.eu/en/details/ee40101s1-999-a/dc12v-fans/sunon/ee40101s1-1000u-999/]

 *

 *                   ┌─────────────────────┐

 *                   │Fan negative terminal│

 *                   └┬────────────────────┘

 *                    │

 *                 │──┘

 *                    │D

 *             G   │──┘

 * [GPIO12]──────┤ │<─┐  2N7002

 *                 │──┤

 *                    │

 *                    │S

 *                   ─┴─

 *                   GND

 *

 * sudo dtc -W no-unit_address_vs_reg -@ -I dts -O dtb -o /boot/overlays/gpio-fan.dtbo gpio-fan.dts

 * sudo nano /boot/config.txt add "dtoverlay=gpio-fan" or "dtoverlay=gpio-fan,gpiopin=12,temp=45000"

 * Build:

 * 	- `sudo dtc -W no-unit_address_vs_reg -@ -I dts -O dtb -o /boot/overlays/gpio-fan.dtbo gpio-fan-overlay.dts`

 * Activate:

 *	- sudo nano /boot/config.txt add "dtoverlay=gpio-fan" or "dtoverlay=gpio-fan,gpiopin=12,temp=45000"

 *	 or

 * sudo sh -c "echo '\n# Enable PI GPIO-Fan\ndtoverlay=gpio-fan\n' >> /boot/config.txt"

 * sudo sh -c "echo '\n# Enable PI GPIO-Fan\ndtoverlay=gpio-fan,gpiopin=12\n' >> /boot/config.txt"

 *	- sudo sh -c 'printf "\n# Enable PI GPIO-Fan Default\ndtoverlay=gpio-fan\n" >> /boot/config.txt'

 *	- sudo sh -c 'printf "\n# Enable PI GPIO-Fan Custom\ntoverlay=gpio-fan,gpiopin=12,temp=45000\n" >> /boot/config.txt'

 *

 */

/dts-v1/;

			trips {

				cpu_hot: trip-point@0 {

					temperature = <55000>;	/* (millicelsius) Fan started at 55°C */

					hysteresis = <5000>;	/* (millicelsius) Fan stopped at 50°C */

					hysteresis = <10000>;	/* (millicelsius) Fan stopped at 45°C */

					type = "active";

				};

			};