iio: dac: ltc2632: use devm_regulator_get_enable_read_voltage()

Simplify the code by using devm_regulator_get_enable_read_voltage().

Some use of dev_err() is replaced with dev_err_probe() to simplify
things even more since we are refactoring these lines anyway.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20241120-iio-regulator-cleanup-round-6-v1-8-d5a5360f7ec3@baylibre.com


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