CIFS: move DFS response parsing out of SMB1 code

since the DFS payload is not tied to the SMB version we can:
* isolate the DFS payload in its own struct, and include that struct in
  packet structs
* move the function that parses the response to misc.c and make it work
  on the new DFS payload struct (add payload size and utf16 flag as a
  result).

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Acked-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>