autofs: make dentry info count consistent

autofs: make dentry info count consistent

If an autofs dentry is a mount root directory there's no ->mkdir() call to
set its count to one.

To make the dentry info count consistent for all autofs dentries set count
to one when the dentry info struct is allocated.

Link: https://lkml.kernel.org/r/165724458671.30914.2902424437132835325.stgit@donald.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>