autofs4: use wake_up() instead of wake_up_interruptible

In "autofs4: use wait_event_killable",  wait_event_interruptible() was
replaced by wait_event_killable(), but in this case we have to use
wake_up() instead of wake_up_interruptible().

In CRIU, we have the autofs test:
https://github.com/checkpoint-restore/criu/blob/master/test/zdtm/static/autofs.c

We run CRIU tests on the linux-next kernels and a few days ago this test
started to fail, actually it hangs up.

I found that wake_up_interruptible() doesn't wake up a thread, which is
waiting.

try_to_wake_up() has the argument "state", it is the mask of task states
that can be woken.

For wake_up_interruptible(), state is TASK_INTERRUPTIBLE.
For wake_up(). state is TASK_NORMAL (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)

If we use wait_event_killable(), the task sleeps in the TASK_KILLABLE
state, so wake_up_interruptible() isn't suitable in this case.

#define TASK_KILLABLE                   (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)

I checked that our test passes with this patch.  I mean that we had a real
problem and we checked that it is fixed by this patch.

Link: http://lkml.kernel.org/r/20180331022839.21277-1-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Acked-by: Ian Kent <raven@themaw.net>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

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