x86/amd: Extend CPU erratum #1474 fix to more affected models

x86/amd: Extend CPU erratum #1474 fix to more affected models

Erratum #1474 has now been extended to cover models from family 17h ranges
00-2Fh, so the errata now covers all the models released under Family
17h (Zen, Zen+ and Zen2).

Additionally extend the workaround to Family 18h (Hygon), since it's based on
the Zen architecture and very likely affected.

Rename all the zen2 related symbols to fam17, since the errata doesn't
exclusively affect Zen2 anymore.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>