staging: unisys: use ATTRIBUTE_GROUPS instead of creating our own

Greg noticed that we were creating our own attribute groups, instead of
using the ATTRIBUTE_GROUPS macro, this patch fixes our mistake.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>