nfsd: cleanup nfsd_file_lru_dispose()

commit 36ebbdb9 upstream.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Cc: Khazhy Kumykov <khazhy@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>