Also start squashing the .mdt files into .mbn and provide compatibility
symlinks so old kernels that look for .mdt still find it.
Also move the zap firmware into a device-specific subdirectory.
Symlinks for venus are skipped since that one's not used in any
production branch yet for sm7225.
[ci:skip-build]: Already built successfully in CI.
Due to symlinks from linux-firmware-ath10k apk is now pulling in
linux-firmware-qcom which already provides a630_sqe.fw.
Since this file is not device/vendor-specific we can really use the file
from linux-firmware and not provide our own. For the record,
a619_gmu.bin also shouldn't be device-specific but currently
linux-firmware doesn't provide that one.
Also just pulling linux-firmware-qcom for this tiny file is pretty space
inefficient but due to the symlink dependency mentioned above, just
removing this file for now from the firmware package removes the file
conflict reported by apk:
ERROR: linux-firmware-qcom-20230919-r1: trying to overwrite lib/firmware/qcom/a630_sqe.fw owned by firmware-fairphone-fp4-adreno-20230215-r1.
[luca: update commit message to reflect dependency situation, update
packaging code a bit]
