Don't directly use OF and use device property APIs. In addition, this
makes the probe() code neater and also allow us to move the
of_device_id table to it's natural place.

While at it, make sure to explicitly include mod_devicetable.h for the
of_device_id table.
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240214-axi-fan-control-no-of-v1-1-43ca656fe2e3@analog.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>