tidy up around finish_automount()

do_add_mount() and mnt_clear_expiry() are not needed outside of
namespace.c anymore, now that namei has finish_automount() to
use.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/internal.h
Simple merge

diff --cc fs/namespace.c
Simple merge