hwmon: (qnap-mcu) Remove (explicitly) unused header

The fwnode.h is not supposed to be used by the drivers as it
has the definitions for the core parts for different device
property provider implementations. Drop it.

Note, that fwnode API for drivers is provided in property.h
which is included here.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250331070600.3985850-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>