Do not use the same rules for loading icon than for upload icon

The loading icon is used in a totally different way than the upload icon
and thus it should not share its CSS rules.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

apps/theming/css/settings-admin.css

@@ -60,8 +60,7 @@ form.uploadButton {
     vertical-align: top;
 }
 
-#theming .icon-upload,
-#theming .icon-loading-small {
+#theming .icon-upload {
     padding: 8px 20px;
     width: 20px;
     margin: 2px 0px;