drm/todo: i915 could use device_link_add

Noticed while reading some unrelated patches. Unfortunately Imre's
patch to add our early/late hooks predated the device_link
infrastructure by 2 years.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Acked-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220132017.30719-1-daniel.vetter@ffwll.ch

Documentation/gpu/todo.rst

@@ -440,5 +440,12 @@ See drivers/gpu/drm/amd/display/TODO for tasks.
 
 Contact: Harry Wentland, Alex Deucher
 
+i915
+----
+
+- Our early/late pm callbacks could be removed in favour of using
+  device_link_add to model the dependency between i915 and snd_had. See
+  https://dri.freedesktop.org/docs/drm/driver-api/device_link.html
+
 Outside DRM
 ===========