Ensure null media player does not crash Telecom.

If the media player could not be initialized, telecom can throw an NPE.
Defensively catching this prevents a crash.
In the bug there appears to be some issues with the audio subsystem.
However, we shouldn't crash the device just because the end call tone
could not play.

Test: Manual.
Bug: 122144736
Change-Id: Ifbfa72b0e4d103201a945d2776f5ca912a04fa1c