smb: client: initialize recv_io->cqe.done = recv_done just once

smb: client: initialize recv_io->cqe.done = recv_done just once

smbdirect_recv_io structures are pre-allocated so we can set the
callback function just once.

This will make it easy to move smbd_post_recv() to common code
soon.

Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>