drm/i915: Complete page table structures

Move the remaining members over to the new page table structures.

This can be squashed with the previous commit if desire. The reasoning
is the same as that patch. I simply felt it is easier to review if split.

v2: In lrc: s/ppgtt->pd_dma_addr[i]/ppgtt->pdp.page_directory[i].daddr/
v3: Rebase.
v4: Rebased after s/page_tables/page_table/.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Michel Thierry <michel.thierry@intel.com> (v2+)
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>