iio: dac: ad5064: convert probe to full device-managed

This change converts the probe of the AD5064 driver to use only
device-managed functions.

The regulator_bulk_disable() is passed on a devm_add_action_or_reset() hook
and the devm_iio_device_register() can be used to register the IIO device.

The driver has both I2C and SPI hooks inside, so all these can be removed.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210913115237.301310-1-aardelean@deviqon.com


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