lxd/firewall/drivers/drivers/xtables: Updates generateFilterIptablesRules to use network-specific chain
lxd/firewall/drivers/drivers/xtables: Updates generateFilterIptablesRules to use network-specific chain

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

stgraber/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,atxwebs/lxd,stgraber/lxd,atxwebs/lxd,atxwebs/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,atxwebs/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,stgraber/lxd