Clear EMMC timeout register to avoid EMMC issue according to cannonlake bios writer guide. BUG=b.71586766 TEST=Install OS into EMMC successfully on meowth P1 platform. Change-Id: I39e927a2c312c94561213f9f7c3319dcafa426b9 Signed-off-by: Lijian Zhao <lijian.zhao@intel.com> Reviewed-on: https://review.coreboot.org/23831 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Nick Vaccaro <nvaccaro@google.com> Reviewed-by: Subrata Banik <subrata.banik@intel.com>