cape: Added support for IIO helper cape

Since we currently can't export the IIO channels from the
ADCs this patch exposes an sysfs entry to read a respective
channel.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
cape: Added example IIO tester dynamics overlay

Added an example usage of the IIO exporter for an current sensor
reading.

Scale factor works with INA169 current sensor at 10k load.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
make sure we register/unregister the NOP xceiver only once

Signed-off-by: Vladimir Pantelic <vladimir@lgf.net>
Extend bone-iio helper

Allow multiple ADC entries.
DT bindinds are extended so you can do:

vsense-name = "AIN1", "AIN3";
vsense-scale = <100 100>;

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
Update iio helper with more channels

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
Add ADC IIO helper