netfilter: PTR_RET can be used

netfilter: PTR_RET can be used

This quiets the coccinelle warnings:

net/bridge/netfilter/ebtable_filter.c:107:1-3: WARNING: PTR_RET can be used
net/bridge/netfilter/ebtable_nat.c:107:1-3: WARNING: PTR_RET can be used
net/ipv6/netfilter/ip6table_filter.c:65:1-3: WARNING: PTR_RET can be used
net/ipv6/netfilter/ip6table_mangle.c:100:1-3: WARNING: PTR_RET can be used
net/ipv6/netfilter/ip6table_raw.c:44:1-3: WARNING: PTR_RET can be used
net/ipv6/netfilter/ip6table_security.c:62:1-3: WARNING: PTR_RET can be used
net/ipv4/netfilter/iptable_filter.c:72:1-3: WARNING: PTR_RET can be used
net/ipv4/netfilter/iptable_mangle.c:107:1-3: WARNING: PTR_RET can be used
net/ipv4/netfilter/iptable_raw.c:51:1-3: WARNING: PTR_RET can be used
net/ipv4/netfilter/iptable_security.c:70:1-3: WARNING: PTR_RET can be used

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>