sbp-target: Fix second argument of percpu_ida_alloc()

Pass a task state as second argument to percpu_ida_alloc().

Fixes: commit 5a3ee221 ("sbp-target: Conversion to percpu_ida tag pre-allocation")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Chris Boot <bootc@bootc.net>