smbios: Rename SMBIOS_ENTRY_POINT_* enums

smbios: Rename SMBIOS_ENTRY_POINT_* enums

Rename the enums to match the naming style used by QAPI, and to
use "32" and "64" instead of "20" and "31".  This will allow us
to more easily move the enum to the QAPI schema later.

About the naming choice: "SMBIOS 2.1 entry point"/"SMBIOS 3.0
entry point" and "32-bit entry point"/"64-bit entry point" are
synonymous in the SMBIOS specification.  However, the phrases
"32-bit entry point" and "64-bit entry point" are used more often.

The new names also avoid confusion between the entry point format
and the actual SMBIOS version reported in the entry point
structure.  For example: currently the 32-bit entry point
actually report SMBIOS 2.8 support, not 2.1.

Based on portions of a patch submitted by Daniel P. Berrangé.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20211026151100.1691925-2-ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>