drm/i915: Set fb->dev early on for inherited fbs

drm/i915: Set fb->dev early on for inherited fbs

We want the fbs inherited from the BIOS to be more or less fully working
prior to actually registering them. This will allow us to just pass the
fb to various helper function instead of having to pass all the
different parameters separately.

Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479498793-31021-18-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>