linux-imx

drm/i915: Prepare to consolidate fence writing

Update the existing architecture specific fence writing routines to
either update the fence to point to a tiled object or to clear them in
preparation to remove the other fence writing routes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>