dt-bindings: iio: magn: add LIS2MDL sensor device binding

Signed-off-by: NLorenzo Bianconi <lorenzo.bianconi@st.com>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/st-sensors.txt

@@ -64,6 +64,7 @@ Magnetometers:
 - st,lsm303dlhc-magn
 - st,lsm303dlm-magn
 - st,lis3mdl-magn
+- st,lis2mdl
 
 Pressure sensors:
 - st,lps001wp-press