boot loader serial console speed to 9600

[Stefan Parvu]

> The ability to change serial console speed from loader(8) only works
> with x86 BIOS calls (and maybe UEFI, not sure). In general, when uboot
> is involved, loader will use whatever serial speed was set up by uboot.

ok, right. Thats exactly probable what we are seeing. We are using a
RBPI3B+ with Strato Base [1] which connects to a Vaisala logger [2]
which cannot speak 115200 due its restrictions to operate on solar panels etc.
So we are experimenting with FreeBSD 12 on this setup to fetch data from
the Vaisala logger. 

> Why do you want to set the console to such a slow speed? It actually
> pisses me off that the standard is as slow as 115200 in the 21st
> century; modern uart chips have no problem running at speeds in the 1-
> 12mbps range.

Because I need to connect the Vaisala logger (which cannot speak 115200) 
to the RBPI3B+ to read data. Using a FDTI cable is simple and probable will
work for us.

Is there anything else we could try to configure ? You mean we could configure
the uboot module ? How ? Any pointers ?

Thanks a lot for tips,
Stefan

[1] https://www.sferalabs.cc/strato-pi/#models <https://www.sferalabs.cc/strato-pi/#models>
[2] https://www.vaisala.com/sites/default/files/documents/QML201C-Datasheet-B210718EN.pdf <https://www.vaisala.com/sites/default/files/documents/QML201C-Datasheet-B210718EN.pdf>