dt-bindings: hwmon: add Microchip LAN966x bindings

Add a binding for the temperature sensor and the fan controller on the
Microchip LAN966x family.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20220401214032.3738095-4-michael@walle.cc
Signed-off-by: Guenter Roeck <linux@roeck-us.net>