Revert "xfs: clear PF_NOFREEZE for xfsaild kthread"

This reverts commit 24ba16b as it
prevents machines from suspending. This regression occurs when the
xfsaild is idle on entry to suspend, and so there s no activity to
wake it from it's idle sleep and hence see that it is supposed to
freeze. Hence the freezer times out waiting for it and suspend is
cancelled.

There is no obvious fix for this short of freezing the filesystem
properly, so revert this change for now.

cc: <stable@vger.kernel.org> # 4.4
Signed-off-by: Dave Chinner <david@fromorbit.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_trans_ail.c

@@ -497,7 +497,6 @@ xfsaild(
 	long		tout = 0;	/* milliseconds */
 
 	current->flags |= PF_MEMALLOC;
-	set_freezable();
 
 	while (!kthread_should_stop()) {
 		if (tout && tout <= 20)