staging:iio:dac: Add AD5421 driver

This patch adds support for the Analog Devices AD5421 Loop-Powered, 4mA to 20mA
DAC.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
4 files changed