Staging: heci: do not print error when heci_bh_handler is already on workqueue

schedule_work returns 0, if the work is already on the work_queue, else
returns non-zero. Do not print error message if heci_bh_handlerwork was
already on queue.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>