ar71xx: fix switch port numbering on RB750r2 and RB750UPr2

This patch fixes the switch port numbering on Mikrotik RB750r2 (hEX lite) and RB750UPr2 (hEX PoE lite).
Tested on a RB750UPr2. Maybe this patch is applicable to other devices (e.g. RB951Ui-2nD, RB952Ui-5ac2nD) but I have no way to test them.

Signed-off-by: João Chaínho <joaochainho@gmail.com>

target/linux/ar71xx/base-files/etc/board.d/02_network

@@ -147,8 +147,6 @@ ar71xx_setup_interfaces()
 	om2p-hsv4|\
 	pb42|\
 	pb44|\
-	rb-750-r2|\
-	rb-750up-r2|\
 	rb-951ui-2hnd|\
 	rb-951ui-2nd|\
 	rb-952ui-5ac2nd|\
@@ -160,6 +158,12 @@ ar71xx_setup_interfaces()
 	wrtnode2q)
 		ucidef_set_interfaces_lan_wan "eth1" "eth0"
 		;;
+	rb-750-r2|\
+	rb-750up-r2)
+		ucidef_set_interfaces_lan_wan "eth1.1" "eth0"
+		ucidef_add_switch "switch0" \
+			"0@eth1" "1:lan:4" "2:lan:3" "3:lan:2" "4:lan:1"
+		;;
 	all0258n|\
 	all0315n|\
 	dlan-hotspot|\