selftests/bpf: Add jit probe_mem corner case tests to s390x denylist

BPF CI fails for s390x with the following result:

  [...]
  All error logs:

  libbpf: prog 'test_jit_probe_mem': BPF program load failed: ERROR: strerror_r(524)=22
  libbpf: prog 'test_jit_probe_mem':
    -- BEGIN PROG LOAD LOG --
    JIT does not support calling kernel function
    processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
    -- END PROG LOAD LOG --
  libbpf: prog 'test_jit_probe_mem': failed to load: -524
  libbpf: failed to load object 'jit_probe_mem'
  libbpf: failed to load BPF skeleton 'jit_probe_mem': -524
  test_jit_probe_mem:FAIL:jit_probe_mem__open_and_load unexpected error: -524
  #89      jit_probe_mem:FAIL
  [...]

Add the test to the deny list.

Fixes: 59fe41b5 ("selftests/bpf: Add verifier test exercising jit PROBE_MEM logic")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>