smb: server: let recv_done() avoid touching data_transfer after cleanup/move

Calling enqueue_reassembly() and wake_up_interruptible(&t->wait_reassembly_queue)
or put_receive_buffer() means the recvmsg/data_transfer pointer might
get re-used by another thread, which means these should be
the last operations before calling return.

Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: 0626e664 ("cifsd: add server handler for central processing and tranport layers")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>