MDL-52673 workshop: fix dndnotsupported message in assessment form

An old CSS rule which doesn't seem to serve any purpose any more was
causing the "drag and drop not supported" message to be displayed (even
when incorrect) in the workshop assessment form when using a list-view
rubric as the grading strategy.

mod/workshop/form/rubric/styles.css

@@ -72,10 +72,6 @@
     border: none;
 }
 
-.path-mod-workshop .assessmentform.rubric.list .fitem .felement span {
-    display: block;
-}
-
 .path-mod-workshop .assessmentform.rubric.list .fitem .felement span input {
     display: block;
     float: left;