fix(multiselect): clear button position (#576)

see telerik/kendo-theme-default#575

scss/multiselect/_layout.scss

@@ -9,6 +9,11 @@
             visibility: hidden;
         }
 
+        .k-clear-value {
+            top: $padding-x-lg / 2;
+            margin-top: 0;
+        }
+
         &[dir='rtl'],
         .k-rtl & {
             li.k-button {