Add support for vsync notification to user space using user events. This is to trigger frame composition based on Vsync. Change-Id: Ie94edfcdb5e540dd2f9a4a5df4bc3b7c4eb9041c Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org> Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>