present: Call present_vblank_scrap in screen mode

This cleans up some code duplication. No functional change.

Signed-off-by: Roman Gilg <subdiff@gmail.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
3 jobs for presentCodeCleanup in 6 minutes and 52 seconds (queued for 1 second)