machine: move possible_cpus to MachineState

so that it would be possible to reuse it with
spapr/virt-aarch64 targets.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/include/hw/boards.h b/include/hw/boards.h
index ac891a8..64e8c07 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -178,6 +178,7 @@
     char *initrd_filename;
     const char *cpu_model;
     AccelState *accelerator;
+    CPUArchIdList *possible_cpus;
 };
 
 #define DEFINE_MACHINE(namestr, machine_initfn) \