[Backport v2022.1.x] ath79-generic: switch Wave2 firmware to -ct

[AiyionPrime]

This partially reverts commit 22c47df.

Devices in ath79-generic like the TP-Link EAP225-Outdoor v1 are really unstable with the non -ct Wave2 firmware and regulary crash with 100% memory consumption when only a handful devices are connected via 5 GHz.

closes #2827

(cherry picked from commit 4badb27)

[herbetom]

Since the switch to -ct the EAP225-Outdoor v1 hasn't experienced the reboots previously seen with the no -ct variant.

However, even with the -ct variant, something is not stable and the node doesn't seem to have 5 GHz connections after a while. This hoewer doesn't seem to affect the rest of the node's operation (no reboot and there still are 2,4 GHz connections).

I see three possible approaches (not sorted):

1. leave it as it is, recommend people with frequent reboots to turn off 5 GHz.
2. switch to -ct and see what happens. As long as it fails really "silently" it's not great, but also less annoying than constant OOM events.
3. end 5 GHz support on the affected devices

I haven't looked more closely at the situation when the node no longer has 5 Ghz connections with the -ct firmware. This means I haven't looked at the logs, I haven't looked at what this looks like on a client, and I haven't looked at how to detect and fix this condition. And i can't tell whether i'll find the time to do so either.

[AiyionPrime]

@bschelm is currently running vH31 (v2022.1.1) on the EAP225v1 devices, as they are unusable with non-ct and the device run without problems with ct.
We have not experienced problems with failing 5GHz on those devices, yet; but I just pinged him about whether he actually did not. I'll report back in a few minutes.

edit linked the wrong gluon tag

[AiyionPrime]

@bschelm just confirmed, only our vH35 ist unstable on these devices; pre non-ct switch is fine.