Update open_data_source documentation to accurately reflect the correct return value on error.
diff --git a/include/hardware/sensors.h b/include/hardware/sensors.h
index 36680d1..a6bee56 100644
--- a/include/hardware/sensors.h
+++ b/include/hardware/sensors.h
@@ -284,7 +284,7 @@
* The caller takes ownership of this handle. This is intended to be
* passed cross processes.
*
- * @return a native_handle_t if successful, < 0 on error
+ * @return a native_handle_t if successful, NULL on error
*/
native_handle_t* (*open_data_source)(struct sensors_control_device_t *dev);