baytrail: snapshot power state in romstage

The memory reference code doesn't maintain some of
the registers which contain valuable information in order
to log correct reset and wake events in the eventlog. Therefore
snapshot the registers which matter in this area so that
they can be consumed by ramstage.

BUG=chrome-os-partner:24907
BRANCH=rambi,squawks
TEST=Did various resets/wakes with logging patch which
     consumes this structure. Eventlog can pick up reset
     events and power failures.

Change-Id: Id8d2d782dd4e1133113f5308c4ccfe79bc6d3e03
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/181982
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/5032
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/lib/cbmem_info.c

@@ -52,6 +52,7 @@ static struct cbmem_id_to_name {
 	{ CBMEM_ID_REFCODE,		"REFCODE    " },
 	{ CBMEM_ID_SMM_SAVE_SPACE,	"SMM BACKUP " },
 	{ CBMEM_ID_REFCODE_CACHE,	"REFCODE $  " },
+	{ CBMEM_ID_POWER_STATE,		"POWER STATE" },
 	{ CBMEM_ID_RAM_OOPS,		"RAMOOPS    " },
 };