commands/setpci: Restrict setpci command when locked down
    
    This command can set PCI devices register values, which makes it dangerous
    in a locked down configuration. Restrict it so can't be used on this setup.
    
    Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
    Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>