iptables: remove bogus address-of

Casts are bad. &curtable is actually of type char (*)[], which is
quite different from what add_argv expects.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/iptables-restore.c b/iptables-restore.c
index 519d480..cd23cfa 100644
--- a/iptables-restore.c
+++ b/iptables-restore.c
@@ -370,7 +370,7 @@
 
 			add_argv(argv[0]);
 			add_argv("-t");
-			add_argv((char *) &curtable);
+			add_argv(curtable);
 
 			if (counters && pcnt && bcnt) {
 				add_argv("--set-counters");