pc: Convert *_MACHINE_OPTIONS macros into functions

By now the new functions will get QEMUMachine as argument, but they will
be later converted to initialize a MachineClass struct directly.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>


