luci-base: luci.model.network: simplify is_auto()
luci-base: luci.model.network: simplify is_auto()

Signed-off-by: Jo-Philipp Wich <bd73d35759d75cc215150d1bbc94f1b1078bee01@mein.io>

openwrt/luci,hnyman/luci,artynet/luci,Noltari/luci,artynet/luci,artynet/luci,tobiaswaldvogel/luci,rogerpueyo/luci,openwrt/luci,nmav/luci,Noltari/luci,nmav/luci,nmav/luci,artynet/luci,hnyman/luci,Noltari/luci,openwrt/luci,Noltari/luci,Noltari/luci,openwrt/luci,rogerpueyo/luci,nmav/luci,lbthomsen/openwrt-luci,nmav/luci,tobiaswaldvogel/luci,rogerpueyo/luci,artynet/luci,openwrt/luci,tobiaswaldvogel/luci,openwrt/luci,nmav/luci,lbthomsen/openwrt-luci,Noltari/luci,hnyman/luci,hnyman/luci,lbthomsen/openwrt-luci,artynet/luci,Noltari/luci,artynet/luci,nmav/luci,tobiaswaldvogel/luci,lbthomsen/openwrt-luci,openwrt/luci,lbthomsen/openwrt-luci,lbthomsen/openwrt-luci,hnyman/luci,artynet/luci,tobiaswaldvogel/luci,openwrt/luci,rogerpueyo/luci,rogerpueyo/luci,hnyman/luci,lbthomsen/openwrt-luci,nmav/luci,tobiaswaldvogel/luci,hnyman/luci,rogerpueyo/luci,hnyman/luci,rogerpueyo/luci,rogerpueyo/luci,artynet/luci,Noltari/luci,lbthomsen/openwrt-luci,tobiaswaldvogel/luci,nmav/luci,Noltari/luci,tobiaswaldvogel/luci