Multi-line comments cleanup (#19535)

Marlin/src/feature/bedlevel/ubl/ubl_motion.cpp

@@ -236,9 +236,7 @@
     }
 
     /**
-     *
      * Generic case of a line crossing both X and Y Mesh lines.
-     *
      */
 
     xy_int8_t cnt = (istart - iend).ABS();