bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()

In the Linux kernel, the following vulnerability has been resolved:

bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()

bpf_map_lookup_percpu_elem() helper is also available for sleepable bpf program. When BPF JIT is disabled or under 32-bit host, bpf_map_lookup_percpu_elem() will not be inlined. Using it in a sleepable bpf program will trigger the warning in bpf_map_lookup_percpu_elem(), because the bpf program only holds rcu_read_lock_trace lock. Therefore, add the missed check.