afs: Fix FS.FetchStatus delivery from updating wrong vnode

The FS.FetchStatus reply delivery function was updating inode of the
directory in which a lookup had been done with the status of the looked up
file.  This corrupts some of the directory state.

Fixes: 5cf9dd55

 ("afs: Prospectively look up extra files when doing a single lookup")
Signed-off-by: David Howells <dhowells@redhat.com>