staging: unisys: merge diagchannel.h to visorbus.h

It is pointless to have a dedicated include for another
include. So I merged them together.

Signed-off-by: Erik Arfvidson <erik.arfvidson@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <Timothy.Sell@unisys.com>
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>