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/Kconfig b/drivers/iio/light/Kconfig
index a022f27..d12b2a0 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -27,6 +27,17 @@
 	 To compile this driver as a module, choose M here: the
 	 module will be called apds9300.
 
+config CM32181
+	depends on I2C
+	tristate "CM32181 driver"
+	help
+	 Say Y here if you use cm32181.
+	 This option enables ambient light sensor using
+	 Capella cm32181 device driver.
+
+	 To compile this driver as a module, choose M here:
+	 the module will be called cm32181.
+
 config CM36651
 	depends on I2C
 	tristate "CM36651 driver"