nfs/flexfiles: fix leak of nfs4_ff_ds_version arrays

commit 1feb26162bee7b2f110facfec71b5c7bdbc7d14d upstream.

The client was freeing the nfs4_ff_layout_ds, but not the contained
nfs4_ff_ds_version array.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>