selftests/bpf: fix test_maps' use of bpf_map_create_opts

Use LIBBPF_OPTS() macro to properly initialize bpf_map_create_opts in
test_maps' tests.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231029011509.2479232-1-andrii@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>