KVM: SVM: Use target APIC ID to complete x2AVIC IRQs when possible

For x2AVIC, the index from incomplete IPI #vmexit info is invalid
for logical cluster mode. Only ICRH/ICRL values can be used
to determine the IPI destination APIC ID.

Since QEMU defines guest physical APIC ID to be the same as
vCPU ID, it can be used to quickly identify the target vCPU to deliver IPI,
and avoid the overhead from searching through all vCPUs to match the target
vCPU.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Message-Id: <20220519102709.24125-16-suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>