[MC][BPF] Add bpf guard for MC test data-section-prefix.ll

Commit f27c4903 ("MC: Add .data. and .rodata. prefixes to MCContext
section classification") added a test assuming bpf target. But it
is possible bpf target is not configured in the clang build.
Let us add explicit bpf-target requirement for the test
so the test can be ingored properly for clang build without enabling
bpf target.