Fix font cache check in QFontEngineFT::recalcAdvances()

Fix font cache check in QFontEngineFT::recalcAdvances()

Cached font was used regardless of the format, resulting in incorrect
advance in some cases when default format differed from the cached
format.

Task-number: QTBUG-24188
Change-Id: I39e4156bd9ba743afa7e106e934c90227fbf2b8b
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
(cherry picked from qtbase/2ea976c3a713535c2419d936d575e0b24545f0fa)
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Lisandro Damián Nicanor Pérez Meyer <perezmeyer@gmail.com>
Reviewed-by: Jiang Jiang <gzjjgod@gmail.com>