x86/CPU/AMD: Print AGESA string from DMI additional information entry

x86/CPU/AMD: Print AGESA string from DMI additional information entry

Type 40 entries (Additional Information) are summarized in section 7.41 as
part of the SMBIOS specification.  Generally, these entries aren't interesting
to save.

However on some AMD Zen systems, the AGESA version is stored here. This is
useful to save to the kernel message logs for debugging. It can be used to
cross-reference issues.

Implement an iterator for the Additional Information entries. Use this to find
and print the AGESA string. Do so in AMD code, since the use case is
AMD-specific.

  [ bp: Match only "AGESA". ]

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Co-developed-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Signed-off-by: "Mario Limonciello (AMD)" <superm1@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Link: https://patch.msgid.link/20260307141024.819807-6-superm1@kernel.org