selftests/bpf: Remove enum64 case from __arg_untrusted test suite

The enum64 type used by verifier_global_ptr_args test case requires
CONFIG_SCHED_CLASS_EXT. At the moment selftets do not depend on this
option. There are just a few enum64 types in the kernel. Instead of
tying selftests to implementation details of unrelated sub-systems,
just remove enum64 test case. Simple enums are covered and that should
be sufficient.

Fixes: 68cca81f ("selftests/bpf: tests for __arg_untrusted void * global func params")
Reported-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Tested-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20250708220856.3059578-1-eddyz87@gmail.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>