staging: unisys: fix sparse warnings

Sparse generates two warnings related to incorrect type in assignment.
This patch changes the types in the struct defined in unisys

Signed-off-by: Andrea Ghittino <aghittino@gmail.com>
Acked-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>