revert Label change

public/app/core/components/Label/Label.tsx

@@ -11,9 +11,7 @@ interface Props {
 
 export const Label: SFC<Props> = props => {
   return (
-    <span
-      className={`gf-form-label width-${props.width ? props.width : '10'} ${props.className ? props.className : ''}`}
-    >
+    <span className={`gf-form-label width-${props.width ? props.width : '10'}`}>
       <span>{props.children}</span>
       {props.tooltip && (
         <Tooltip className="gf-form-help-icon--right-normal" placement="auto" content={props.tooltip}>