build: include kmod-ipt-offload in default images

Netfilter flow offload has now started to become useful and suitable for
a wider testing audience. Configuring it via UCI is also integrated in
firewall3 by adding 'option flow_offloading 1' to the 'defaults'
section in /etc/config/firewall

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/target.mk

@@ -17,7 +17,7 @@ DEFAULT_PACKAGES:=base-files libc libgcc busybox dropbear mtd uci opkg netifd fs
 # For nas targets
 DEFAULT_PACKAGES.nas:=block-mount fdisk lsblk mdadm
 # For router targets
-DEFAULT_PACKAGES.router:=dnsmasq iptables ip6tables ppp ppp-mod-pppoe firewall odhcpd-ipv6only odhcp6c
+DEFAULT_PACKAGES.router:=dnsmasq iptables ip6tables ppp ppp-mod-pppoe firewall odhcpd-ipv6only odhcp6c kmod-ipt-offload
 DEFAULT_PACKAGES.bootloader:=
 
 ifneq ($(DUMP),)