iio: add Capella CM32181 ambient light sensor driver.

Add Capella Microsystem CM32181 Ambient Light Sensor IIO driver.
This driver will convert raw data to lux value under open-air
condition. Change the calibscale based on the cover material.

Signed-off-by: Kevin Tsai <ktsai@capellamicro.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index daa327f..60e35ac 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -5,6 +5,7 @@
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
+obj-$(CONFIG_CM32181)		+= cm32181.o
 obj-$(CONFIG_CM36651)		+= cm36651.o
 obj-$(CONFIG_GP2AP020A00F)	+= gp2ap020a00f.o
 obj-$(CONFIG_HID_SENSOR_ALS)	+= hid-sensor-als.o