SF: do not skip validate if it is called more than a vsync earlier

To prevent an early present, we don't want to skip validate and
present immediately if we started the frame to early. Instead we will
do the validate and wait before calling to present. The reason why we
can't wait before validate, is that we might need to do client
composition after validate (based on hwc composition strategy)
and we might miss a frame if we waited before validate.


Bug: 187871031
Test: observe systraces
Change-Id: I9b4b0d4c9c58ddc703bcddadd44dfb0e7eff1cbd