We can drop some duplicate code if we use devm_action for disabling
regulators and pm and the managed variant of iio_device_register().

This allows us to completely remove all remove() callbacks from both
i2c and spi code.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>