drm/i915: Apply the full CPU domain markup before freezing

Let's not take any chances by using a shortcut to mark the objects as in
the CPU domain upon freezing (all pages will be written to disk and so
on restore all objects will start from the CPU domain). Currently, we
simply mark the objects as being in the CPU domain, bypassing the
flushes. Let's call the full domain transfer function so that we have
less special case code (and symmetry with the suspend path) even though
it will be mostly redundant.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180601144125.18026-2-chris@chris-wilson.co.uk