dt-bindings: hwmon: gpio-fan: Convert txt bindings to yaml

Convert fan devices connected to GPIOs to the YAML syntax.

Signed-off-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231209171653.85468-1-david@ixit.cz
Signed-off-by: Guenter Roeck <linux@roeck-us.net>