To answer my own question and as a reminder for myself ...

quoted

I applied this and tried comple testing, and got this warning:

  DTC     arch/arm/boot/dts/aspeed-bmc-tyan-s7106.dtb
../arch/arm/boot/dts/aspeed-bmc-tyan-s7106.dts:217.4-14: Warning
(reg_format): /ahb/apb/bus at 1e78a000/i2c-bus at 40/nct7802 at 28/channel at 0:reg:
property has invalid length (4 bytes) (#address-cells == 2,
#size-cells == 1)

Is there an easy way for me to see these types of warnings? Or should
they really come out as errors?

Yes, there is:

1) Copy the .config from the OpenBMC build directory:
cp ~/src/openbmc/build/s7106/tmp/work/s7106-openbmc-linux-gnueabi/linux-aspeed/5.15+gitAUTOINC+da6376d789-r0/linux-s7106-standard-build/.config
.

2) Run
ARCH="arm" make aspeed-bmc-tyan-s7106.dtb


Oskar.