[platforms/drm] Allow running without outputs
Summary:
Set outputs enablement also when none outputs are present. This patch is
similar to earlier attempt at D17985.
BUG: 402827
BUG: 389551
BUG: 398680
BUG: 413758
Test Plan:
Starting without outputs, manual disconnects and DPMS changes. There is still
an issue when an output gets disconnected while the DPMS is off. But it's an
improvement already.
Reviewers: KWin, davidedmundson
Reviewed By: KWin, davidedmundson
Subscribers: kwin
Tags: KWin
Maniphest Tasks: T10016
Differential Revision: https://phabricator.kde.org/D26511