iio: potentiostat: add LMP91000 support

Add support for the LMP91000 potentiostat which is used for chemical
sensing applications.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 87e4c43..2b6e276 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -29,6 +29,7 @@
 obj-y += magnetometer/
 obj-y += orientation/
 obj-y += potentiometer/
+obj-y += potentiostat/
 obj-y += pressure/
 obj-y += proximity/
 obj-y += temperature/