This is in preparation for adding Raspberry Pi 3 B+ support, for which we’ll
need to let the firmware locate the DTB file under file names such as
bcm2710-rpi-3-b-plus.dtb.
Note that short names are not upper-cased currently (the standard says they
should, but neither the firmware nor the linux kernel care) so that upgrades
from older gokrazy installations work. In a year or so, we can change this.
