Mwan3 interface limit

@feckert Is there still a 250 interface limit on Mwan3 or was that removed at some point? I couldn't find such a limit in the script. If not then the GUI should probably be updated to reflect this change as well as the documentation.

I think there is a 64 interface limit now, at least it was when I used it a couple months ago.

The max interface limit is defined by this config option

The default value is 0x3F00 that means we have 126 available mark for the firewall.
As far as I can remember, with this configuration the maximum number of interfaces is 123 or 122.
I'm not quite sure anymore. I would have to check the sources first to see what it was like exactly.
So I remembered we need a marker for


And the rest would be for the interfaces

It was 250 before but I had no idea if it was possible to change it in the config. Although I think in LuCI it shows 64 probably (AFAIR) but I am not sure now because I don't use it anymore.

I've been looking at this again.
The Calculation how much interfaces are possible based on the mmx_mask option could be found in the source of luci-app-mwan3

If You set mmx_mask to to 0xFF00 as before we could manage 252 interfaces.