drm: document drm_mode_create_lease object requirements

validate_lease expects one CRTC, one connector and one plane.

Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Cc: Keith Packard <keithp@keithp.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210903130000.1590-1-contact@emersion.fr

include/uapi/drm/drm_mode.h

@@ -1110,6 +1110,9 @@ struct drm_mode_destroy_blob {
  * struct drm_mode_create_lease - Create lease
  *
  * Lease mode resources, creating another drm_master.
+ *
+ * The @object_ids array must reference at least one CRTC, one connector and
+ * one plane if &DRM_CLIENT_CAP_UNIVERSAL_PLANES is enabled.
  */
 struct drm_mode_create_lease {
 	/** @object_ids: Pointer to array of object ids (__u32) */