hw/i386: Move arch_id decode inside x86_cpus_init

Apicid calculation depends on knowing the total number of numa nodes
for EPYC cpu models. Right now, we are calculating the arch_id while
parsing the numa(parse_numa). At this time, it is not known how many
total numa nodes are configured in the system.

Move the arch_id calculation inside x86_cpus_init. At this time, smp
parse is already completed and numa node information is available.

Override the handlers if use_epyc_apic_id_encoding is enabled in
cpu model definition.

Also replace the calling convention to use handlers from
X86MachineState.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Message-Id: <158396724217.58170.12256158354204870716.stgit@naples-babu.amd.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>