[MinnowBoard] Early serial output

[Simon Glass]

Hi,

I see in coreboot there is code to print UART messages in the
romstage, but nothing appears until romstage_main_continue() is
called. This is quite late - both the CAR init and FSP init have
completed by this point.

Is there any way to get earlier serial output? I don't think the board
has visible POST codes so serial seems to be the only option.

Regards,
Simon