mb/intel/shadowmountain: Enable early EC Software Sync

BUG=None
TEST=Build and boot to OS on shadowmountain. Ensure that the
EC Software Sync is complete.

Signed-off-by: Usha P <usha.p@intel.com>
Change-Id: I8648db685d9c63ed1f2b3e599ca951d6648b7baf
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52416
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Balaji Manigandan <balaji.manigandan@intel.com>
Reviewed-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>

src/mainboard/intel/shadowmountain/Kconfig

@@ -31,12 +31,12 @@ config CHROMEOS
 	select GBB_FLAG_FORCE_DEV_BOOT_USB
 	select GBB_FLAG_FORCE_DEV_BOOT_ALTFW
 	select GBB_FLAG_FORCE_MANUAL_RECOVERY
-	select GBB_FLAG_DISABLE_EC_SOFTWARE_SYNC
 
 config VBOOT
 	select EC_GOOGLE_CHROMEEC_SWITCHES
 	select VBOOT_LID_SWITCH
 	select HAS_RECOVERY_MRC_CACHE
+	select VBOOT_EARLY_EC_SYNC
 
 config DIMM_SPD_SIZE
 	int