staging: unisys: combine visorchannel.h and visorbus.h

Combine the include files visorchannel.h and visorbus.h so that only one
include file is needed for the .c files.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>