Allow skipping unknown MBP rather than bailing out. Change-Id: I9a54858c37d73e320de77aea5a05ab5dcf67cd69 Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com> Reviewed-on: http://review.coreboot.org/5976 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin <adurbin@google.com>