CHERRY-PICK: Peppy: Fix handling of 2GB config

Use the most significant bit of spd index to determine dimm count.

BUG=chrome-os-partner:20663
BRANCH=none
TEST=none: need to wait for the new hardware.

Change-Id: I71bb9fc9bc6d416a58fe6114e1f5f86b5d877d0b
Reviewed-on: https://gerrit.chromium.org/gerrit/60834
Reviewed-by: Shuo-Peng Liao <deanliao@chromium.org>
Commit-Queue: Gediminas Ramanauskas <gedis@chromium.org>
Tested-by: Gediminas Ramanauskas <gedis@chromium.org>
1 file changed