[platforms/drm] At safety checks for the properties
Summary:
The AMS code accesses elements in a vector which might not be valid. This
change refactors the code to be more robust, especially the DrmPlane,
which started to crash after adding transformation support.
BUG: 386490
Reviewers: KWin, Plasma, fvogt, subdiff
Subscribers: plasma-devel, kwin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D8752