lantiq: fix network in failsafe

So far the network in failsafe is setup only for one board. Use the
eth0 interface as lan interface for all boards for now.

If a board has its lan interface(s) on another eth, a special
handling based on the board name can be added.

Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/lantiq/base-files/lib/preinit/05_set_preinit_iface_lantiq

@@ -3,15 +3,7 @@
 . /lib/functions/lantiq.sh
 
 set_preinit_iface() {
-
-	board=$(lantiq_board_name)
-
-	case "$board" in
-	TDW8970)
-		ifname=eth0
-		;;
-	esac
-
+	ifname=eth0
 }
 
 boot_hook_add preinit_main set_preinit_iface