drm/todo: Add bootsplash entry

Ease entry for anyone wanting to pick up the bootsplash work by providing
a couple of pointers.

v2: Add Sam as contact (Sam)

Signed-off-by: Noralf Trønnes <[e-mail]>
Reviewed-by: Paul Kocialkowski <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/gpu/todo.rst

···
   device_link_add to model the dependency between i915 and snd_had. See
   https://dri.freedesktop.org/docs/drm/driver-api/device_link.html
 
+Bootsplash
+==========
+
+There is support in place now for writing internal DRM clients making it
+possible to pick up the bootsplash work that was rejected because it was written
+for fbdev.
+
+- [v6,8/8] drm/client: Hack: Add bootsplash example
+  https://patchwork.freedesktop.org/patch/306579/
+
+- [RFC PATCH v2 00/13] Kernel based bootsplash
+  https://lkml.org/lkml/2017/12/13/764
+
+Contact: Sam Ravnborg
+
 Outside DRM
 ===========