drm/atomic-helper: WARN if fake_commit->hw_done is not completed as expected

For real commits we WARN if ->hw_done hasn't been completed by the time
drm_atomic_helper_commit_cleanup_done() is called. Let's do the same for
the fake commit.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181122143412.11655-2-ville.syrjala@linux.intel.com


Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>