staging: unisys: diagchannel.h: get rid of unused fields

Some more churn of the drivers have made more fields unused, get
rid of them.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>