Revert "drm/i915: Improve on suspend / resume time with VT-d enabled"

This reverts commit 2ef6efa7.

Checking the presence if the IRST (Intel Rapid Start Technology)
through the ACPI to decide whether to rebuild or not the GGTT
puts us at the mercy of the boot firmware and we need to
unnecessarily rely on third parties.

Because now we avoid adding scratch pages to the entire GGTT we
don't need this hack anymore.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221130235805.221010-6-andi.shyti@linux.intel.com