util/intelmetool: Fix some platforms

Bootguard:
* Fix Mac support (ME_version can't be detected)
* Skip MSR read on older platforms (as it would fail anyway)
* Refactor MSR error handling
* Print Bootguard state "Unknown" on MSR read error

Change-Id: Iafe3f5c22c6caeedc556933405b9f6d83ec876a1
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/22598
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
2 files changed