iio: accel: fxls8962af: Switch from of specific to fwnode based properties.

Only the irq was retrieved using an of specific accessor. Switch to the
fwnode equivalent and adjust headers. Also include missing mod_devicetable.h
and irq.h.

Cc: Sean Nyekjaer <sean@geanix.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240218172731.1023367-8-jic23@kernel.org


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>