drm/docs: Fix todo.rst

I didnt' format the thing correctly :-(

Fixes: 39aead83 ("fbcon: Disable accelerated scrolling")
Reviewed-by: Simon Ser <contact@emersion.fr>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201118073637.597206-1-daniel.vetter@ffwll.ch