dim/drm-misc: Add rule to not push patches with issues

We kinda left this out, and I like the wording from the drm-intel
side, so add that. Motivated by a discussion with Christian.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Cc: Christian König <christian.koenig@amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>