Add generic driver to support sigma delta modulators.
Typically, this device is hardware connected to
an IIO device in charge of the conversion. Devices are
bonded through the hardware consumer API.
Signed-off-by: NArnaud Pouliquen <arnaud.pouliquen@st.com>
Acked-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NMark Brown <broonie@kernel.org>