Add check for empty vsync data in Choreographer.

Currently there is a codepath in native DisplayEventDispatcher
introduced by aosp fc690e2a2d1d3cf08d71a02c4ecd14665c0f2039.
It accounts for vsync timeout. Here in java choreographer, we don't want
to divide by zero for logging messages so a check is added. There are no
real logic changes.

Test: atest ChoreographerTest
Bug: 229685140
Change-Id: I80f24abb89b9d961b017aca93340b1b02af6f66c