Use mx_AuthBody prefix for consistency

src/components/views/auth/LanguageSelector.js

@@ -32,7 +32,7 @@ export default function LanguageSelector() {
     if (SdkConfig.get()['disable_login_language_selector']) return <div />;
 
     const LanguageDropdown = sdk.getComponent('views.elements.LanguageDropdown');
-    return <LanguageDropdown className="mx_Auth_language"
+    return <LanguageDropdown className="mx_AuthBody_language"
         onOptionChange={onChange}
         value={getCurrentLanguage()}
     />;