smb: smbdirect: introduce smbdirect_connection_rdma_{established,event_handler}()

smb: smbdirect: introduce smbdirect_connection_rdma_{established,event_handler}()

This will be used by client and server in future,
it will be used after the rdma connection is established
in order to simplify the events happening on an established
connection.

We'll also have smbdirect_{connect,accept}_rdma_event_handler
functions which will be used before the rdma connection is
established.

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>