netifd: improve reloading behaviour

git-svn-id: svn://svn.openwrt.org/openwrt@36903 3c298f89-4303-0410-b956-a3cf2f4a3e73
ppp: correctly handle address when reloading

git-svn-id: svn://svn.openwrt.org/openwrt@36904 3c298f89-4303-0410-b956-a3cf2f4a3e73