[SvgIcon] Remove unused style assignment

Author: mbrookes

src/SvgIcon/SvgIcon.js

@@ -79,10 +79,7 @@ class SvgIcon extends Component {
       prepareStyles,
     } = this.context.muiTheme;
 
-    const offColor = color ? color :
-      style && style.fill ? style.fill :
-        'currentColor';
-
+    const offColor = color ? color : 'currentColor';
     const onColor = hoverColor ? hoverColor : offColor;
 
     const mergedStyles = Object.assign({