Fix this compiling error:

   TEST-OBJ [test_progs] mptcp.test.o
 /home/tgl/mptcp_net-next/tools/testing/selftests/bpf/prog_tests/mptcp.c: In function ‘run_test’:
 /home/tgl/mptcp_net-next/tools/testing/selftests/bpf/prog_tests/mptcp.c:63:2: error: ‘bpf_map__next’ is deprecated: libbpf v0.7+: use bpf_object__next_map() instead [-Werror=deprecated-declarations]
   map = bpf_map__next(NULL, obj);
   ^~~
 In file included from ./test_progs.h:33:0,
                  from /home/tgl/mptcp_net-next/tools/testing/selftests/bpf/prog_tests/mptcp.c:2:
 /home/tgl/mptcp_net-next/tools/testing/selftests/bpf/tools/include/bpf/libbpf.h:685:17: note: declared here
  struct bpf_map *bpf_map__next(const struct bpf_map *map, const struct bpf_object *obj);
                  ^~~~~~~~~~~~~
 cc1: all warnings being treated as errors
 make: *** [Makefile:488: /home/tgl/mptcp_net-next/tools/testing/selftests/bpf/mptcp.test.o] Error 1

Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 tools/testing/selftests/bpf/prog_tests/mptcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index 0e65d64868e9..04aef0f147dc 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -60,7 +60,7 @@ static int run_test(int cgroup_fd, int server_fd, bool is_mptcp)
 		return -1;
 	}
 
-	map = bpf_map__next(NULL, obj);
+	map = bpf_object__next_map(obj, NULL);
 	map_fd = bpf_map__fd(map);
 
 	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
-- 
2.34.1