Do not always use the smoothScaled routine, the normal routines are
also optimized, and do not convert to alpha formats when not necessary.
Task-number: QTBUG-49719
Change-Id: I6ee9b620cc259472c419e7363357f41ce29b594a
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>