backends/drm: enable pipelines for VR headsets

Otherwise, the pipeline state from an earlier hotplug scenario can leave
the pipeline disabled and without a CRTC, which means leasing the output
will fail

BUG: 487938
FIXED-IN: 6.1.0

src/backends/drm/drm_gpu.cpp

@@ -289,6 +289,8 @@ bool DrmGpu::updateOutputs()
             Q_EMIT outputAdded(output);
             pipeline->setLayers(m_platform->renderBackend()->createDrmPlaneLayer(pipeline, DrmPlane::TypeIndex::Primary), m_platform->renderBackend()->createDrmPlaneLayer(pipeline, DrmPlane::TypeIndex::Cursor));
             pipeline->setActive(!conn->isNonDesktop());
+            // only "enable" VR headsets here; Workspace makes this decision for normal outputs
+            pipeline->setEnable(conn->isNonDesktop());
             pipeline->applyPendingChanges();
         }
         if (stillExists) {