drm/i915: Use 128k alignment for untiled display surface on i965 (v2)

drm/i915: Use 128k alignment for untiled display surface on i965 (v2)

The original i965, including the revised G35 and Q35, requires an
alignment of 128K for the display surface with linear memory, so
increase the requirement from 64k for these chipsets. For the later
chipsets in the i965 family, only a 4k alignment is required. (So
long as we do not start performing asynchronous flips.)

Note the impact of this should be slight as on i965 we should be using a
tiled frontbuffer for anything up to a 4096x4096 display.

v2: compilation fixes and note that the docs do not exclude the G35 from
the extra alignment.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>