It's not that easy, because what you see there are not actually MTD partitions. Rather they are UBI volumes living on a UBI device which uses an actual MTD partition. New device-tree bindings will have to be introduced for that, both UBI device to MTD device (that's quite easy and @hauke has suggested that in the past and got rejected, I've also tried this more recently) and also UBI volumes (for which it will be even more tricky to convince upstream maintainers).