soc/intel/apollolake: Implement global reset handling

Global reset enable bit is not cleared on reset. Therefore, clear
the bit early. Lock down 0xcf9 so that payload/OS can't issue
global reset.

BUG=chrome-os-partner:54149
BRANCH=none
TEST=none

Change-Id: I3ddf6dd82429b725c818bcd96e163d2ca0acd308
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/15199
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)
3 files changed