backends/drm: only enable HDR if both display and driver are capable of it

The config may have HDR or WCG enabled, and the driver or display settings changed
since then to make it impossible to actually enable either.
The config values stay unchanged when this happens, so reconnecting the display with
HDR support will automatically turn it on again.

BUG: 481518

src/backends/drm/drm_output.cpp

@@ -348,7 +348,9 @@ bool DrmOutput::queueChanges(const std::shared_ptr<OutputChangeSet> &props)
 
 ColorDescription DrmOutput::createColorDescription(const std::shared_ptr<OutputChangeSet> &props) const
 {
-    if (props->highDynamicRange.value_or(m_state.highDynamicRange) && m_connector->edid()) {
+    const bool screenSupportsHdr = m_connector->edid()->isValid() && m_connector->edid()->supportsBT2020() && m_connector->edid()->supportsPQ();
+    const bool driverSupportsHdr = m_connector->colorspace.isValid() && m_connector->hdrMetadata.isValid() && (m_connector->colorspace.hasEnum(DrmConnector::Colorspace::BT2020_RGB) || m_connector->colorspace.hasEnum(DrmConnector::Colorspace::BT2020_YCC));
+    if (props->highDynamicRange.value_or(m_state.highDynamicRange) && driverSupportsHdr && screenSupportsHdr) {
         const auto colorimetry = props->wideColorGamut.value_or(m_state.wideColorGamut) ? NamedColorimetry::BT2020 : NamedColorimetry::BT709;
         const auto nativeColorimetry = m_information.edid.colorimetry().value_or(Colorimetry::fromName(NamedColorimetry::BT709));
         const auto sdrBrightness = props->sdrBrightness.value_or(m_state.sdrBrightness);