smb: client: let smbd_destroy() wait for SMBDIRECT_SOCKET_DISCONNECTED

We should wait for the rdma_cm to become SMBDIRECT_SOCKET_DISCONNECTED,
it turns out that (at least running some xfstests e.g. cifs/001)
often triggers the case where wait_event_interruptible() returns
with -ERESTARTSYS instead of waiting for SMBDIRECT_SOCKET_DISCONNECTED
to be reached.

Or we are already in SMBDIRECT_SOCKET_DISCONNECTING and never wait
for SMBDIRECT_SOCKET_DISCONNECTED.

Fixes: 050b8c37 ("smbd: Make upper layer decide when to destroy the transport")
Fixes: e8b3bfe9 ("cifs: smbd: Don't destroy transport on RDMA disconnect")
Fixes: b0aa92a2 ("smb: client: make sure smbd_disconnect_rdma_work() doesn't run after smbd_destroy() took over")
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>
Signed-off-by: Steve French <stfrench@microsoft.com>