Show summary of "Add user" item

The summary of "Add user" item is not displayed.
To show it, useAdminDisabledSummary should be false.

Bug: 30005296
Change-Id: Ia33cab4d671f42bd971acbf5523da1c4d21948e1

src/com/android/settings/users/UserSettings.java

@@ -223,6 +223,7 @@ public class UserSettings extends SettingsPreferenceFragment
             mMePreference.setSummary(R.string.user_admin);
         }
         mAddUser = (DimmableIconPreference) findPreference(KEY_ADD_USER);
+        mAddUser.useAdminDisabledSummary(false);
         // Determine if add user/profile button should be visible
         if (mUserCaps.mCanAddUser && Utils.isDeviceProvisioned(getActivity())) {
             mAddUser.setOnPreferenceClickListener(this);