Based on some new (to me...) info from Purism's Sebastian K, there are
apparently Evergreen devices that return different values for board rev,
so we shouldn't assume only r4 are Evergreen, and default to the r2 DT.
But many earlier devices (Birch, Chestnut, Dogwood) may or may not have
the board rev set either. Who knows! Defaulting to the Evergreen DT on
these devices is bad too, but there weren't many of those shipped (I
guess?), at least not compared to the number of Evergreens that aren't
properly identifiable in u-boot... so this using this DT by default is
the best of the two bad options we have.
This comment thread has more info:
https://gitlab.com/postmarketOS/pmaports/-/issues/1643#note_1147248594fixes#1643
[ci:skip-build] already built successfully in CI
Using uInitrd is no longer necessary. I'm not sure *why*, but it just
works using the non-u-boot-image initramfs. The post-upgrade script was
changed to clean up the old images from /boot/u{Image,Initrd}, restoring
a lot of free space in that partition (~25MB)
This also sneaks in a small 1 character change to silence removing the
gpsd service from the default runlevel
[ci:skip-build]: already built successfully in CI
