hwmon: fix potential sensor registration fail if of_node is missing

hwmon: fix potential sensor registration fail if of_node is missing

It is not sufficient to check of_node in current device.
In some cases, this would cause the sensor registration to fail.

This patch looks for device's ancestors to find a valid of_node if any.

Fixes: d560168b5d0f ("hwmon: (core) New hwmon registration API")
Signed-off-by: Phinex Hung <phinex@realtek.com>
Link: https://lore.kernel.org/r/20230321060224.3819-1-phinex@realtek.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>