Add constants for fast path resume copying

Add constants for fast path resume copying

cache as ram does not usually cache the ram before it is up. Hence,
if romstage.c backs up resume memory, the involved memcpy is always
uncached. This makes resume very slow.
On Sandybridge we copy the memory later, after enabling caching, and
that allows us to resume in as little as 250ms.

Change-Id: I31a71ad4468679d39880cf9a8c4e497bb7addf8f
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/872
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)