cifs: get rid of smb_vol->UNCip and smb_vol->port

Passing this around as a string is contorted and painful. Instead, just
convert these to a sockaddr as soon as possible, since that's how we're
going to work with it later anyway.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>