This patch makes the AMS execution path work with the new DrmCrtc and
DrmBuffer structure and solves major issues about:
* VT switching
* DPMS
* Hot plugging
* Logout
* Memory leaks

Test Plan:
Tested with Gl and QPainter.

Reviewers: #kwin

Subscribers: kwin, #kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D5191