net: caif: fix double disconnect client in chnl_net_open()

When connecting to client timeout, disconnect client for twice in
chnl_net_open(). Remove one. Compile tested only.

Fixes: 2aa40aef

 ("caif: Use link layer MTU instead of fixed MTU")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>