Hide "Play TTS sample" when locale is not settable as default

Due to a bug, it's possible for settings to show status telling
that locale is available, despite locale not being in list of
locales settable as TTS default locale. This change fixes it.

Bug: 10630713
Change-Id: I21f8487fc6c1ea7812aeffbc26dfa5fc0a8afa3b
1 file changed