iio: adc: max11100: Use devm_ functions for rest of probe()

By using devm_add_action_or_reset() to manage the regulator disable,
it becomes simple to use managed functions for all of remove.
This simplifies error handling and allows us to drop the remove()
function entirely.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210516172520.1398835-3-jic23@kernel.org