smb: client: use disable[_delayed]_work_sync in smbdirect.c

This makes it safer during the disconnect and avoids
requeueing.

It's ok to call disable[delayed_]work[_sync]() more than once.

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
Fixes: 050b8c37 ("smbd: Make upper layer decide when to destroy the transport")
Fixes: f198186a ("CIFS: SMBD: Establish SMB Direct connection")
Fixes: c7398583 ("CIFS: SMBD: Implement RDMA memory registration")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>