staging: unisys: Move visorchannel into visorbus

visorchannel seems to be a necessary component to visorbus and can never
function as a standalone module.  Let's treat it like a visorbus feature
that is always enabled.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>