broadwell: Implement Recovery Button

This patch fixes the use of the recovery button, and the value is stored
in a SATA controller scratch register.

BUG=chrome-os-partner:35241
BRANCH=none
TEST=Use recovery button and run firmware_RecoveryButton

Change-Id: Ia06f147c7e44d6c4eea2c2e4f502c233c956ee9b
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 34c7ee922a9602b3448a72cd669fd68feeed1bba
Original-Change-Id: I1667c7f188b0f87c4bc7caa82f9c977b2b4c0611
Original-Signed-off-by: Ryan Lin <ryan.lin@intel.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/241772
Original-Reviewed-by: Shawn N <shawnn@chromium.org>
Reviewed-on: http://review.coreboot.org/9811
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/soc/intel/broadwell/romstage/romstage.c

@@ -80,6 +80,10 @@ void * asmlinkage romstage_main(unsigned long bist,
 	/* Call into mainboard. */
 	mainboard_romstage_entry(&rp);
 
+#if CONFIG_CHROMEOS
+	save_chromeos_gpios();
+#endif
+
 	return setup_stack_and_mttrs();
 }