iio: Add ABI documentation for illuminance raw and scale values in light

This patchset adds ABI documentation for the following attributes:

in_illuminance_scale, used atleast once in al3320a staging/iio/light/
in_illuminance_calibscale, used atleast once in cm32181
in_illuminance_input, used in cm3232 at least once
in_illuminance_raw used atleast once in al3320a
in_illuminance_clear_raw and in_illuminance_ir_raw exposed by
gp2ap020a00f with modifiers IIO_MOD_LIGHT_CLEAR and
IIO_MOD_LIGHT_IR respectively.

Signed-off-by: Darshana Padmadas <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/ABI/testing/sysfs-bus-iio

···
 What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_humidityrelative_scale
 What:		/sys/bus/iio/devices/iio:deviceX/in_velocity_sqrt(x^2+y^2+z^2)_scale
+What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance_scale
 KernelVersion:	2.6.35
 Contact:	[e-mail]
 Description:
···
 what		/sys/bus/iio/devices/iio:deviceX/in_proximity0_calibscale
 What:		/sys/bus/iio/devices/iio:deviceX/in_pressureY_calibscale
 What:		/sys/bus/iio/devices/iio:deviceX/in_pressure_calibscale
+What:		/sys/bus/iio/devices/iio:deviceX/in_illuminance_calibscale
 KernelVersion:	2.6.35
 Contact:	[e-mail]
 Description:
···
 		values should behave in the same way as a distance, i.e. lower
 		values indicate something is closer to the sensor.
 
+What:		/sys/.../iio:deviceX/in_illuminance_input
+What:		/sys/.../iio:deviceX/in_illuminance_raw
 What:		/sys/.../iio:deviceX/in_illuminanceY_input
 What:		/sys/.../iio:deviceX/in_illuminanceY_raw
 What:		/sys/.../iio:deviceX/in_illuminanceY_mean_raw
+What:		/sys/.../iio:deviceX/in_illuminance_ir_raw
+What:		/sys/.../iio:deviceX/in_illuminance_clear_raw
 KernelVersion:	3.4
 Contact:	[e-mail]
 Description: