waterlevel: Patching up doxygen comments

Signed-off-by: John Van Drasek <john.r.van.drasek@intel.com>

src/waterlevel/waterlevel.h

    * @ingroup gpio waterlevel
    */
   /**
-   * @library libupm-waterlevel
+   * @library waterlevel
    * @sensor waterlevel
    * @comname waterlevel
    * @type liquid