[platforms/drm] Disable transformations

Summary:
Rotation in the past was not working in the DRM backend reliable. Now on 5.17
it even freezes the KWin session, so for now we need to just disable it trying.

Test Plan:
Tried to change Rotation with KScreen. Nothing happened but session was still
usable afterwards.

Reviewers: #kwin

Subscribers: ngraham, jriddell, bshah, zzag, apol, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D24112