ramips: mt7621: fix failsafe mode networking

Disable VLANs on mt7621 boards with mt7530 switches on failsafe entry.

Allows failsafe networking to work correctly.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
[fixed default case syntax error]
Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips

@@ -6,17 +6,22 @@
 . /lib/ramips.sh
 
 ramips_set_preinit_iface() {
-	RT3X5X=`cat /proc/cpuinfo | egrep "(RT3.5|RT5350|MT7628|MT7688|MT7620)"`
+	RT3X5X=`cat /proc/cpuinfo | egrep "(RT3.5|RT5350|MT7628|MT7688|MT7620|MT7621)"`
 
 	if [ -n "${RT3X5X}" ]; then
 		# The ethernet switch driver enables VLAN by default, but
 		# failsafe uses eth0, making the device unreachable:
 		# https://dev.openwrt.org/ticket/18768
-		ralink_switchdev=rt305x
 		case "${RT3X5X}" in
 		*MT7620*)
 			ralink_switchdev=mt7620
 			;;
+		*MT7621*)
+			ralink_switchdev=mt7530
+			;;
+		*)
+			ralink_switchdev=rt305x
+			;;
 		esac
 		swconfig dev $ralink_switchdev set reset 1
 		swconfig dev $ralink_switchdev set enable_vlan 0