compositor-drm: simplify drm_output_find_by_crtc()

As CRTC is allocated on output enable and deallocated on output disable,
there cannot be any matches in find-by-crtc from the
pending_output_list.

Remove the loop over pending_output_list as never finding anything by
definition.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Derek Foreman <derekf@osg.samsung.com>

libweston/compositor-drm.c

@@ -796,12 +796,6 @@ drm_output_find_by_crtc(struct drm_backend *b, uint32_t crtc_id)
 			return output;
 	}
 
-	wl_list_for_each(output, &b->compositor->pending_output_list,
-			 base.link) {
-		if (output->crtc_id == crtc_id)
-			return output;
-	}
-
 	return NULL;
 }