Make a general call to voicemail when calling back from call log.

A voicemail call log entry is saved with the number of the voicemail
that was called. In the multi-sim case, however, we don't want to call
back to the voicemail number of the original call because it might be
the number of a different phone account.

Bug: 17925501
Change-Id: I528c4039cc227608e040ae71b6b10488376fb357