[IPV6] SYSCTL: Fix possible memory leakage in error path.
In error path, we do need to free memory just allocated.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
YOSHIFUJI Hideaki%!s(int64=17) %!d(string=hai) anos