staging: unisys: Convert bus functions to pass bus_info pointer around

Most bus functions pass bus_no around and then do a lookup inside each
function to find the bus_info struct.  Instead just pass the pointer.

This prepares us for a later conversion to using visor_device.

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>