tools/bpf: fix two test_btf unit test cases

There are two unit test cases, which should encode
TYPEDEF type, but instead encode PTR type.
The error is flagged out after enforcing name
checking in the previous patch.

Fixes: c0fa1b6c ("bpf: btf: Add BTF tests")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>