dt-bindings: st_sensors: add st,lis2hh12 compatible entry

Add LIS2HH12 compatible entry.
Signed-off-by: Gaëtan André <rvlander@gaetanandre.eu>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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

@@ -50,6 +50,7 @@ Accelerometers:
 - st,lis3dhh
 - st,lis3de
 - st,lis2de12
+- st,lis2hh12
 
 Gyroscopes:
 - st,l3g4200d-gyro