smb: server: fix leak of active_num_conn in ksmbd_tcp_new_connection()

In the Linux kernel, the following vulnerability has been resolved:

smb: server: fix leak of active_num_conn in ksmbd_tcp_new_connection()

On kthread_run() failure in ksmbd_tcp_new_connection(), the transport is

freed via free_transport(), which does not decrement active_num_conn,

leaking this counter.

Replace free_transport() with ksmbd_tcp_disconnect().