[package] firewall (#7355)

[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	  since the values gathered by scan_interfaces() may be outdated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

SVN-Revision: 21502