selftests/bpf: Keep verifier_map_ptr exercising ops pointer access

selftests/bpf: Keep verifier_map_ptr exercising ops pointer access

sashiko complained that 38498c0ebacd ("selftests/bpf: Adjust verifier_map_ptr
for the map's excl field") would slightly decrease the test coverage given
before the test was against the verifier rejecting the ops pointer. Recover
the old test with the right offsets and add the existing one as an additional
test case.

  # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_map_ptr
  [    1.672932] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  #637/1   verifier_map_ptr/bpf_map_ptr: read with negative offset rejected:OK
  #637/2   verifier_map_ptr/bpf_map_ptr: read with negative offset rejected @unpriv:OK
  #637/3   verifier_map_ptr/bpf_map_ptr: write rejected:OK
  #637/4   verifier_map_ptr/bpf_map_ptr: write rejected @unpriv:OK
  #637/5   verifier_map_ptr/bpf_map_ptr: read non-existent field rejected:OK
  #637/6   verifier_map_ptr/bpf_map_ptr: read non-existent field rejected @unpriv:OK
  #637/7   verifier_map_ptr/bpf_map_ptr: read beyond excl field rejected:OK
  #637/8   verifier_map_ptr/bpf_map_ptr: read beyond excl field rejected @unpriv:OK
  #637/9   verifier_map_ptr/bpf_map_ptr: read ops field accepted:OK
  #637/10  verifier_map_ptr/bpf_map_ptr: read ops field accepted @unpriv:OK
  #637/11  verifier_map_ptr/bpf_map_ptr: r = 0, map_ptr = map_ptr + r:OK
  #637/12  verifier_map_ptr/bpf_map_ptr: r = 0, map_ptr = map_ptr + r @unpriv:OK
  #637/13  verifier_map_ptr/bpf_map_ptr: r = 0, r = r + map_ptr:OK
  #637/14  verifier_map_ptr/bpf_map_ptr: r = 0, r = r + map_ptr @unpriv:OK
  #637     verifier_map_ptr:OK
  [...]
  Summary: 2/20 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260602133052.423725-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>