MST topology needs to be suspended so we don't have any calls to
fbdev after it's finalized. MST will be destroyed later as part of
drm_mode_config_cleanup().

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109964Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191127021609.162700-1-jose.souza@intel.com