selftests/bpf: Remove entries from config.{arch} already present in config

selftests/bpf: Remove entries from config.{arch} already present in config

`config.{arch}` had entries already present in `config`.

When generating the config used by vmtest, concatenate the `config` file
with the `config.{arch}` one, making those entries duplicated, so remove
those duplications.

Use the following command to get the differences:

  $ comm -1 -2  <(sort tools/testing/selftests/bpf/config.x86_64) <(sort tools/testing/selftests/bpf/config)
  $ comm -1 -2  <(sort tools/testing/selftests/bpf/config.aarch64) <(sort tools/testing/selftests/bpf/config)
  $ comm -1 -2  <(sort tools/testing/selftests/bpf/config.riscv64) <(sort tools/testing/selftests/bpf/config)
  $ comm -1 -2  <(sort tools/testing/selftests/bpf/config.ppc64el) <(sort tools/testing/selftests/bpf/config)
  $ comm -1 -2  <(sort tools/testing/selftests/bpf/config.s390x) <(sort tools/testing/selftests/bpf/config)

This is similar with commit 7a42af4b94f1 ("selftests/bpf: Remove entries
from config.s390x already present in config").

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250826065057.11415-1-yangtiezhu@loongson.cn