Adding support for TP-Link RE190 v4 (AC750 2.4/5GHz Wi-Fi Range Extender)

[jedboy]

@edupaag If you decide to open device and add serial, here are some pics of RE220. I think it is impossible to open without breaking the case.

TP-Link RE220 V3 hardware support

See also TP-Link RE220 V1 I did connect to serial on V1 and was able to run initramfs from re220-v2. It mostly worked. In referenced post, I looked at the differences for the re220-v2 and various re200 models. Didn't see much different. I'm just not sure how to take the next step. Question for devs: Is the .id value in the platform.sh defined solely in OpenWRT code or does it have to match some existing value from the hardware? For the serial connection, the holes are there. The case is…