staging: unisys: added display string size define

Display string size that is guaranteed to be no longer the 99 characters.

Don't use a magic number throughout the code, define it once and use it
throughout.

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