This is deprecated, also drop the comment about faults.

v2: also use ttm_sg_tt_init to avoid allocating the page array.
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/403835/