smb: smbdirect: introduce smbdirect_connection_send_immediate_work()

smb: smbdirect: introduce smbdirect_connection_send_immediate_work()

This is a combination of smb_direct_send_immediate_work() in the server
as well as send_immediate_empty_message() and smbd_post_send_empty() in
the client.

smbdirect_connection_send_immediate_work() replace all of them in
client and server.

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>