ramips: add a workaround to fix failsafe on RT5350

Due to TCP connections not working when VLAN is disabled, this is
needed to get failsafe functional.
Signed-off-by: Paul Fertser <fercerpav@gmail.com>

Backport of r42179

git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@42358 3c298f89-4303-0410-b956-a3cf2f4a3e73

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

@@ -11,7 +11,24 @@ ramips_set_preinit_iface() {
 		swconfig dev rt305x set reset 1
 	fi
 
-	ifname=eth0
+	if echo $RT3X5X | grep -q RT5350; then
+		# This is a dirty hack to get by while the switch
+		# problem is investigated. When VLAN is disabled, ICMP
+		# pings work as expected, but TCP connections time
+		# out, so telnetting in failsafe is impossible. The
+		# likely reason is TCP checksumming hardware getting
+		# disabled:
+		# https://www.mail-archive.com/openwrt-devel@lists.openwrt.org/msg19870.html
+		swconfig dev rt305x set enable_vlan 1
+		swconfig dev rt305x vlan 1 set ports "0 6"
+		swconfig dev rt305x port 6 set untag 0
+		swconfig dev rt305x set apply 1
+		vconfig add eth0 1
+		ifconfig eth0 up
+		ifname=eth0.1
+	else
+		ifname=eth0
+	fi
 }
 
 boot_hook_add preinit_main ramips_set_preinit_iface