iio: adis16475: make use of the new unmasked_drdy flag

The library can now handle enabling/disabling IRQs for devices that
cannot unmask the data ready pin. Hence there's no need to provide an
'enable_irq' callback anymore.

The library will also automatically request the IRQ with 'IRQF_NO_AUTOEN'
so that we can also remove that from the driver.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210903141423.517028-4-nuno.sa@analog.com


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