[beagleboard] Disable serial consol on ttyO0

One for Robert I'm guessing, unless anyone else can help!

How could I disable the serial console on ttyO0. Our hardware engineers
have used this for a device I need to talk to, which I can do after the
board has booted by disabling /etc/init/serial.conf however I think the
board still dumps info on this port during boot, which is bad for our device
and I need to power up the external device after boot to stop it going
crazy... Not good.

Well, obviously... He should have used one of the other "4" ports...

I see /boot/SOC.sh specifies serial_tty=ttyO0 and also I think I can set
console= in the uEnv.txt, however playing with these stops the board

Is there a ncie clean way?

first: rebuild u-boot, in the build/config you can specify which of usart.
2nd: change console=ttyOx,115200 to the new usart
3rd: adjust /etc/init/serial.conf