libbpf: Fix BPF_PROBE_READ{_STR}_INTO() on s390x

BPF_PROBE_READ_INTO() and BPF_PROBE_READ_STR_INTO() should map to
bpf_probe_read() and bpf_probe_read_str() respectively in order to work
correctly on architectures with !ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230128000650.1516334-24-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>