don't set clang target as its already handled in bindgen by default

[liebman]

There is no need to set the clang_target as its already being defaulted to TARGET. Besides passing the rust target is wrong for some targets as llvm's targets are slightly different (see this mapping) causing it to fail on some TARGETS with:

  error: unknown target triple 'riscv32imac-unknown-none-elf'
  thread 'main' panicked at /Users/chris.l/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bindgen-0.69.4/ir/context.rs:556:15:
  libclang error; possible causes include:
  - Invalid flag syntax
  - Unrecognized flags
  - Invalid flag arguments
  - File I/O errors
  - Host vs. target architecture mismatch
  If you encounter an error missing from this list, please file an issue or a PR!

[robin-nitrokey]

Good catch, thank you! I’ve squashed the commits, added a changelog entry and will merge after adding some CI checks to the repository.