Get rid of uevent VSYNC= but don't try proper vsync

This is a simpler patch - it just disables the old UEVENT vsync message but doesn't try to do proper vsync. I'm pretty sure nothing in userspace wants that message any more (grepping the tree) - the qcom legacy hwcomposer just falls back to the userspace 16ms timer, the same as before. So the only difference should be reduced CPU from things that listen for uevents.