iio: adc: ti-ads8344: convert probe to device-managed

This change converts the driver to register via devm_iio_device_register().
The regulator disable is moved on a devm_add_action_or_reset() hook.

And the spi_set_drvdata() isn't required anymore.
And finally, the ads8344_remove() can be removed as well.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210903073707.46892-1-aardelean@deviqon.com


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