autofs: make disc device user accessible

The autofs miscellanous device ioctls that shouldn't require
CAP_SYS_ADMIN need to be accessible to user space applications in order
to be able to get information about autofs mounts.

The module checks capabilities so the miscelaneous device should be fine
with broad permissions.

Link: http://lkml.kernel.org/r/150216641928.11652.7388977863125547969.stgit@pluto.themaw.net


Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Colin Walters <walters@redhat.com>
Cc: Ondrej Holy <oholy@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>