RPi serial ports revisited

[Per olof Ljungmark]

Last year I managed with the help of this list and googling to get a Pi3 
running with the Adafruit GPS Hat.
That was FreeBSD 12.0-CURRENT #0 r336479

Now I've got a Raspberry Pi 3 B+ and wanted to check if I could get it 
to run the hat with
FreeBSD 12.0-STABLE r348832 PPS  arm64

Well, as it turned out, a lot of things changed since, both on the Pi 
and FreeBSD.
I've gotten as far as I have the correct GPS output on /dev/cuau1 but I 
want it on /dev/cuau0

So with 12-STABLE, where and how do I switch GPIO pins between uart0 and 
uart1?

Thanks,

//per