netfilter: don't xt_jumpstack_alloc twice in xt_register_table

In xt_register_table, xt_jumpstack_alloc is called first, later
xt_replace_table is used. But in xt_replace_table, xt_jumpstack_alloc
will be used again. Then the memory allocated by previous xt_jumpstack_alloc
will be leaked. We can simply remove the previous xt_jumpstack_alloc because
there aren't any users of newinfo between xt_jumpstack_alloc and
xt_replace_table.

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jan Engelhardt <jengelh@medozas.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-By: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>