main/linux-postmarketos-allwinner: use zstd-compressed firmware
main/linux-postmarketos-allwinner: support zstd-compressed firmware
This is in preparation for aports/linux-firmware switching to zstd compression in https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/60282
main/firmware-pine64-ov5640: compress with zstd
This uses the same settings as aports/linux-firmware will use with https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/60282
main/firmware-pine64-rtl8723bt: compress with zstd
This uses the same settings that aports/linux-firmware will use with https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/60282