net/smc: fixes for converting from "struct smc_cdc_tx_pend **" to "struct smc_wr_tx_pend_priv *"

"struct smc_cdc_tx_pend **" can not directly convert
to "struct smc_wr_tx_pend_priv *".

Fixes: 2bced6ae

 ("net/smc: put slot when connection is killed")
Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>