drivers: iio: admv1013: add vcc regulators

Add regulators for the VCC supplies of the admv1013.

The patch aims to align the implementation with the current admv1014
driver where all the VCC supplies are handled as regulators.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Link: https://lore.kernel.org/r/20230731094455.26742-2-antoniu.miclaus@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>