gluon-core: remove unused lantiq case

There was never a device with a dedicated WAN port supported in Gluon
which could make use of such a workaround.

As the only relevant lantiq-xrx200 target now uses swconfig anyways,
we can remove this workaround.

Signed-off-by: David Bauer <mail@david-bauer.net>

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

@@ -62,16 +62,6 @@ elseif platform.match('ath79', 'generic', {
 	'ubnt,unifiac-pro',
 }) then
 	lan_ifname, wan_ifname = 'eth0.2', 'eth0.1'
-elseif platform.match('lantiq') then
-	local switch_data = board_data.switch or {}
-	local switch0_data = switch_data.switch0 or {}
-	local roles_data = switch0_data.roles or {}
-	for _, role_data in ipairs(roles_data) do
-		if role_data.role == 'wan' then
-			wan_ifname = iface_exists(role_data.device)
-			break
-		end
-	end
 elseif platform.match('ramips', 'mt7621', {
 	'netgear,wac104',
 }) then