luci-base: fix luci.sys.wifi.getiwinfo() on radio names

Fall back to using a phy-wide iwinfo handle if the vif query yields no result.

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

modules/luci-base/luasrc/sys.lua

@@ -453,8 +453,18 @@ wifi = {}
 
 function wifi.getiwinfo(ifname)
 	ntm.init()
-	local wnet = ntm.wifinet(ifname)
-	return wnet.iwinfo or { ifname = ifname }
+
+	local wnet = ntm:get_wifinet(ifname)
+	if wnet and wnet.iwinfo then
+		return wnet.iwinfo
+	end
+
+	local wdev = ntm:get_wifidev(ifname)
+	if wdev and wdev.iwinfo then
+		return wdev.iwinfo
+	end
+
+	return { ifname = ifname }
 end