- Set fixed commit in "source" line to avoid future problems if some
change is pushed to the repository
- Add pmb:cross-native to build natively since these are just a few
copy operations
- Remove some unneeded `cd "$srcdir"` lines
- Avoid installing venus.mbn since this is just a combined version of
venus.mdt + venus.b*
- Split -wcnss subpackage into -wcnss and -wcnss-nv to allow replacing
the WCNSS firmware with a newer version from firmware-qcom-db410c
- Provide "firmware-qcom-msm8916-wcnss" to still allow switching to
the original firmware if wanted
- Install only WCNSS_qcom_wlan_nv.bin for aarch64 since the other
configuration files are only needed for downstream (armv7)
