[NETFILTER]: annotate xtables targets with const and remove casts

net/ipv4/netfilter/ipt_CLUSTERIP.c

net/ipv4/netfilter/ipt_ECN.c

net/ipv4/netfilter/ipt_LOG.c

net/ipv4/netfilter/ipt_REJECT.c

net/ipv4/netfilter/ipt_recent.c

net/ipv4/netfilter/nf_nat_rule.c

net/ipv6/netfilter/ip6t_REJECT.c

net/ipv6/netfilter/ip6t_ipv6header.c

net/ipv6/netfilter/ip6t_rt.c

net/netfilter/xt_CONNSECMARK.c

net/netfilter/xt_RATEEST.c

net/netfilter/xt_connlimit.c

net/netfilter/xt_dccp.c

net/netfilter/xt_esp.c

net/netfilter/xt_multiport.c

net/netfilter/xt_policy.c

net/netfilter/xt_rateest.c

net/netfilter/xt_sctp.c

net/netfilter/xt_tcpmss.c

net/netfilter/xt_tcpudp.c