The VisionFive2 Tumbleweed image provides a dtb for the MilkV Mars
(jh7110-milkv-mars.dtb), which doesn't work with the MilkV Mars Compute Module.

In order to get the dtb working with the Compute Module, I needed to replace
the `cap-mmc-highspeed` setting with `cap-sd-highspeed` for `mmc@16010000`.

I tested this both on a MilkV Mars CM with eMMC and without eMMC, and in both
cases the Kernel wouldn't find a root filesystem by using the default dtb.

I don't have a MilkV Mars to test if cap-mmc-highspeed is correct there, but it
looks to me like at least for the Mars CM we should provide a different dtb so
that it works out of the box.

This is part of my Hackweek project, see also
https://codeberg.org/grisu48/Mars-CM/src/branch/main/dtb