soc/intel/xeon_sp: Work around FSP-T not respecting its own API

soc/intel/xeon_sp: Work around FSP-T not respecting its own API

The CPX FSP-T does not respect the FSP2.x spec and uses registers where
coreboot has its initial timestamp stored.

If the initial timestamp is later than some other timestamps this
messes up the timestamps 'cbmem -t' reports as it thinks they are a
result from a timestamp overflow (reporting that it took 100k years to
boot).

TEST: The ocp/deltalake boots within the span of a lifetime.

Change-Id: I4ba15decec22cd473e63149ec399d82c5e3fd214
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47738
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>