qemu_hotplug: move qemuDomainDetachDeviceLive() to qemu_hotplug.c
    
    This function is going to take on some of the functionality of its
    subordinate functions, which all live in qemu_hotplug.c.
    
    qemuDomainDetachDeviceControllerLive() is only called from
    qemuDomainDetachDeviceLive() (and will soon be merged into
    qemuDomainDetachControllerDevice(), which is in qemu_hotplug.c), so
    it is also moved.
    
    Signed-off-by: Laine Stump <laine@laine.org>
    ACKed-by: Peter Krempa <pkrempa@redhat.com>