[package] firewall (#7355)

	- partially revert r21486, start firewall on init again
	- skip iface hotplug events if base fw is not up yet
	- get ifname and up state with uci_get_state() in iface setup
	  since the values gathered by scan_interfaces() may be outdated
	  when iface coldplugging happens (observed with pptp)
	- ignore up state when bringing down interfaces because ifdown
	  reverts state vars before dispatching the iface event
	- bump package revision

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@21502 3c298f89-4303-0410-b956-a3cf2f4a3e73