net/smc: unlock on error paths in __smc_setsockopt()

These two error paths need to release_sock(sk) before returning.

Fixes: a6a6fe27 ("net/smc: Dynamic control handshake limitation by socket options")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: D. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>