staging: unisys: remove incorrect error handling after queue_delayed_work

The queue_delayed_work() return false if the work is
already on the queue, true otherwise.
So return value cannot be less than zero.

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>