Cannot switch between multiple TTS engines

That is caused by layout xml changes. The radio button was clickable
in old xml resource. But it is not clickable in new xml resource.
Therefore we can't receive click callback. Fixed by changing
Radio button state when preference is clicked.

Fixes: 135285101
Test: manual, make RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.tts"
Change-Id: Idd7bf37d9ccbc1b56d41978d19dc05c8a81cc49a