pc: acpi: drop cpu->found_cpus bitmap

pc: acpi: drop cpu->found_cpus bitmap

cpu->found_cpus bitmap is used for setting present
flag in CPON AML package. But it takes a bunch of code
to fill bitmap and could be simplified by getting
presense info from possible CPUs list directly.

So drop cpu->found_cpus bitmap and unroll possible
CPUs list into APIC index array at the place where
CPUON AML package is created.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>