netfilter: nf_conntrack_standalone: Fix set-but-unused variables.

The variable 'ret' is set but unused in ct_seq_show().

This was obviously meant to be used to propagate error codes
to the caller, so make it so.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_standalone.c

@@ -245,7 +245,7 @@ static int ct_seq_show(struct seq_file *s, void *v)
 	ret = 0;
 release:
 	nf_ct_put(ct);
-	return 0;
+	return ret;
 }
 
 static const struct seq_operations ct_seq_ops = {