present: Remove superfluous set abort flip function in window mode

The function is never called from present_screen.c in contrast to the behavior
in screen mode.

In present_wnmd.c we can simply remove the function which does an unnecessary
check of the property before setting it and directly set the property at the
two locations the function was called previously.

Signed-off-by: Roman Gilg <subdiff@gmail.com>
6 jobs for present-refactor in 4 minutes and 51 seconds (queued for 1 second)