Nothing special, except the somewhat awkward split in probe helper
callbacks between here and drm_crtc_funcs.

v2: Suggestions from Thierry.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449218769-16577-25-git-send-email-daniel.vetter@ffwll.chReviewed-by: Thierry Reding <treding@nvidia.com>