[PATCH bpf] selftests/bpf: add missing pointer dereference for map stacktrace fixup

I get a segfault without it, other fixups always do dereference, and
without dereference I don't understand how it can ever work.

Fixes: 7c85c448e7d74 ("selftests/bpf: test_verifier, check
bpf_map_lookup_elem access in bpf prog")

Signed-off-by: Stanislav Fomichev <redacted>
---
  tools/testing/selftests/bpf/test_verifier.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index df6f751cc1e8..d23929a1985d 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c

@@ -14166,7 +14166,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_map_type prog_type,
  		do {
  			prog[*fixup_map_stacktrace].imm = map_fds[12];
  			fixup_map_stacktrace++;
-		} while (fixup_map_stacktrace);
+		} while (*fixup_map_stacktrace);
  	}
  }