Added basic support for Lightware SF20/LW20 I2C connected LIDAR Devices

src/drivers/sf1xx/sf1xx.cpp

@@ -260,6 +260,13 @@ SF1XX::init()
 		_conversion_interval = 50000;
 		break;
 
+        case 5:
+                /* SF20/LW20 (100m 48-388Hz) */
+                _min_distance = 0.001f;
+                _max_distance = 100.0f;
+                _conversion_interval = 20834;
+                break;
+
 	default:
 		DEVICE_LOG("invalid HW model %d.", hw_model);
 		return ret;