iio: adc: add max11410 adc driver

Adding support for max11410 24-bit, 1.9ksps delta-sigma adc which
has 3 differential reference and 10 differential channel inputs.
Inputs and references can be buffered internally. Inputs can also
be amplified with internal PGA.

Device has four digital filter modes: FIR50/60, FIR50, FIR60 and SINC4.
FIR 50Hz and 60Hz rejections can be enabled/disabled separately.
Digital filter selection affects sampling frequency range so driver
has to consider the configured filter when configuring sampling frequency.

Signed-off-by: Ibrahim Tilki <Ibrahim.Tilki@analog.com>
Link: https://lore.kernel.org/r/20221003105903.229-2-Ibrahim.Tilki@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>