qemu_hotplug: make Detach functions called only from qemu_hotplug.c static
    
    These are no longer called from qemu_driver.c, since the function that
    called them (qemuDomainDetachDeviceLive()) has been moved to
    qemu_hotplug.c, and they are no longer called from testqemuhotplug.c
    because it now just called qemuDomainDetachDeviceLive() instead of all
    the subordinate functions.
    
    Signed-off-by: Laine Stump <laine@laine.org>
    ACKed-by: Peter Krempa <pkrempa@redhat.com>