[CIFS] Fix check for tcon seal setting and fix oops on failed mount from earlier patch

set tcon->ses earlier

If the inital tree connect fails, we'll end up calling cifs_put_smb_ses
with a NULL pointer. Fix it by setting the tcon->ses earlier.

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>