r17453: Fix msdfs RPC management (this broke with the autogenerated dfs rpcs).

r17453: Fix msdfs RPC management (this broke with the autogenerated dfs rpcs).

* Remove "unknown" from dfs_Enum (samba4 dfs IDL updates to follow).

* When encountering an unsupported infolevel the rpc server must reply
with a dfs_info_0 structure and WERR_OK (observed from w2k3 when talking
to nt4).

Guenther
(This used to be commit f9bef1f08f7d2a4c95c28329ac73e8646f033998)