gluon-core, gluon-setup-mode: reset ifname sysconfigs on each update, introduce single_ifname

Allow interface names to change on updates to handle hwconfig -> DSA and
similar migrations.

On devices with only a single interface, a sysconfig single_ifname is
created instead of wan_ifname or lan_ifname to allow separate
configuration in site.conf.

package/gluon-core/luasrc/lib/gluon/upgrade/020-interfaces

 #!/usr/bin/lua
 
-local sysconfig = require 'gluon.sysconfig'
-
--- Are we already set up?
-if sysconfig.lan_ifname or sysconfig.wan_ifname then
-	os.exit(0)
-end
-
-
 local platform = require 'gluon.platform'
-local site = require 'gluon.site'
+local sysconfig = require 'gluon.sysconfig'
 
 local json = require 'jsonc'
 local uci = require('simple-uci').cursor()
@@ -69,13 +61,11 @@ end
 if wan_ifname and lan_ifname then
 	sysconfig.wan_ifname = wan_ifname
 	sysconfig.lan_ifname = lan_ifname
+	sysconfig.single_ifname = nil
 else
-	local single_ifname = lan_ifname or wan_ifname
-	if site.single_as_lan(false) then
-		sysconfig.lan_ifname = single_ifname
-	else
-		sysconfig.wan_ifname = single_ifname
-	end
+	sysconfig.wan_ifname = nil
+	sysconfig.lan_ifname = nil
+	sysconfig.single_ifname = lan_ifname or wan_ifname
 end
 
 

package/gluon-setup-mode/luasrc/lib/gluon/upgrade/320-setup-ifname

@@ -3,13 +3,8 @@
 local platform = require 'gluon.platform'
 local sysconfig = require 'gluon.sysconfig'
 
-
-if sysconfig.setup_ifname then
-	os.exit(0)
-end
-
 if platform.is_outdoor_device() then
-	sysconfig.setup_ifname = sysconfig.wan_ifname or sysconfig.lan_ifname
+	sysconfig.setup_ifname = sysconfig.single_ifname or sysconfig.wan_ifname
 else
-	sysconfig.setup_ifname = sysconfig.lan_ifname or sysconfig.wan_ifname
+	sysconfig.setup_ifname = sysconfig.single_ifname or sysconfig.lan_ifname
 end