selftests/bpf: fix test_align

since commit 82abbf8d the verifier rejects the bit-wise
arithmetic on pointers earlier.
The test 'dubious pointer arithmetic' now has less output to match on.
Adjust it.

Fixes: 82abbf8d

 ("bpf: do not allow root to mangle valid pointers")
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>