Summary: Like we do on inverted mode

Test Plan: Not much, because we don't support portrait mode on intel hardware just yet. I can see the cursor properly rotated before drm tells us to fall back to the previous configuration.

Reviewers: #kwin, #plasma, graesslin

Reviewed By: #kwin, #plasma, graesslin

Subscribers: zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D19710