x86/microcode/AMD: Select which microcode patch to load

x86/microcode/AMD: Select which microcode patch to load

All microcode patches up to the proper BIOS Entrysign fix are loaded
only after the sha256 signature carried in the driver has been verified.

Microcode patches after the Entrysign fix has been applied, do not need
that signature verification anymore.

In order to not abandon machines which haven't received the BIOS update
yet, add the capability to select which microcode patch to load.

The corresponding microcode container supplied through firmware-linux
has been modified to carry two patches per CPU type
(family/model/stepping) so that the proper one gets selected.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Waiman Long <longman@redhat.com>
Link: https://patch.msgid.link/20251027133818.4363-1-bp@kernel.org