platforms/drm: Fix handling of missing EDID
drmModeGetPropertyBlob() may return null and we should handle that. In addition to that, m_conn is not initialized in DrmConnector so kwin will crash whenever the connector info is accessed.
drmModeGetPropertyBlob() may return null and we should handle that. In addition to that, m_conn is not initialized in DrmConnector so kwin will crash whenever the connector info is accessed.