selftests/bpf: Add F_NEEDS_EFFICIENT_UNALIGNED_ACCESS to some tests

Some verifier tests were missing F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
which made the test fail. Add the flag where needed.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230705113926.751791-2-bjorn@kernel.org