drm/i915: allow tiled front buffers on 965+

This patch corrects a pretty big oversight in the KMS code for 965+
chips.  The current code is missing tiled surface register programming,
so userland can allocate a tiled surface and use it for mode setting,
resulting in corruption.  This patch fixes that, allowing for tiled
front buffers on 965+.

Cc: stable@kernel.org
Tested-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>