DisplayEventDisplatcher: Quiet down dispatcher Vsync pulse messages

My logcat is packed with these dispatcher vsync pulse messages
that really don't seem to be describing an error case (though
maybe I'm wrong?).

So quiet it down a bit and set the loglevel to verbose.

Change-Id: Ic4359f64f9cecfc1ffe49275f5f63327ba1b6f1d
Signed-off-by: John Stutlz <john.stultz@linaro.org>