smbios: On attach, print the entry point version and revision

Additionally, on verbose boot, print the entry point revision as
a diagnostic/debugging help.

PR: 284460
Reviewed by: markj, imp (both older version)
MFC after: 2 weeks
Event: February src bug-busting session
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D49179