iio: proximity: add support for PulsedLight LIDAR

Add support for the PulsedLight LIDAR rangefinder sensor which allows
high speed (over 300Hz) distance measurements using Barker Coding within
40 meter range.

Support only tested on the "blue label" rev 2, but may work using low
sample frequencies on the original version.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>