FS#3239 - VLAN tagging on ipq40xx (GL-B1300) no longer works

[openwrt-bot]

fntmx:

GL-B1300, ipq40xx, 19.07-SNAPSHOT

https://forum.openwrt.org/t/vlan-tagging-on-ipq40xx-gl-b1300-no-longer-works/69569

The config below used to create VLAN 3 & 4 on the LAN ports, but not after the commit https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=8c191712558ce945993982b03abc5ce80e0fe230 : LAN clients cannot get their IP addresses

I build 19.07 WITHOUT that commit and it fixed the issue.

config switch
option name 'switch0'
option reset '1'
option enable_vlan '1'

config switch_vlan
option device 'switch0'
option vlan '3'
option vid '3'
option ports '3 0t'

config switch_vlan
option device 'switch0'
option vlan '4'
option vid '4'
option ports '4 0t'

[openwrt-bot]

PolynomialDivision:

Please read my commit message and test with my PR. If it works, can I add u as tested by?
#3596