drm/i915/guc: Stop using fence/status from CTB descriptor

Stop using fence/status from CTB descriptor as future GuC ABI will
no longer support replies over CTB descriptor.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210603051630.2635-8-matthew.brost@intel.com