AppArmor: Fix the error case for chroot relative path name lookup

When a chroot relative pathname lookup fails it is falling through to
do a d_absolute_path lookup.  This is incorrect as d_absolute_path should
only be used to lookup names for namespace absolute paths.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees@ubuntu.com>