Revert "Add TASKQ_NORECLAIM flag"

This reverts commit 372c257233.  The
use of the PF_MEMALLOC flag was always a hack to work around memory
reclaim deadlocks.  Those issues are believed to be resolved so this
workaround can be safely reverted.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

module/spl/spl-taskq.c

@@ -442,10 +442,6 @@ taskq_thread(void *args)
 	tq = tqt->tqt_tq;
         current->flags |= PF_NOFREEZE;
 
-	/* Disable the direct memory reclaim path */
-	if (tq->tq_flags & TASKQ_NORECLAIM)
-		current->flags |= PF_MEMALLOC;
-
         sigfillset(&blocked);
         sigprocmask(SIG_BLOCK, &blocked, NULL);
         flush_signals(current);