treewide: avoid "More than one maintainer" error

Alpine's abuild is soon going to complain if an APKBUILD has more than one "Maintainer:" listed. Work around it by renaming the additional maintainers to "Maintainer2:", "Maintainer3:" etc. While at it, move the devicepkg reference link to the top in device-xiaomi-santoni for consistency.

In postmarketOS, we require at least two maintainers for devices in main, therefore it does not make sense to drop additional maintainers from the file.

In Alpine, this change was made because pkgs.alpinelinux.org apparently can't handle more than one maintainer. I looked into it, and it would require a database change to add it there, so it does not seem worth the effort. I also thought about extending abuild to add an environment variable to skip the check, but then the package would not build with plain abuild without using the env var.

Related: https://gitlab.alpinelinux.org/alpine/abuild/-/commit/dd4cd9d606f5e28f382414e258af562e346c6ab5