autofs4: Clean up inode operations

Since the use of ->follow_link() has been eliminated there is no
need to separate the indirect and direct inode operations.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>