bpf, selftests: Fix cast to smaller integer type 'int' warning in raw_tp

Fix warning in bpf selftests,

progs/test_raw_tp_test_run.c:18:10: warning: cast to smaller integer type 'int' from 'struct task_struct *' [-Wpointer-to-int-cast]

Change int type cast to long to fix. Discovered with gcc-9 and llvm-11+
where llvm was recent main branch.

Fixes: 09d8ad16885ee ("selftests/bpf: Add raw_tp_test_run")
Signed-off-by: John Fastabend <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Link: https://lore.kernel.org/bpf/160134424745.11199.13841922833336698133.stgit@john-Precision-5820-Tower

tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c

···
 	count++;
 	if ((__u64) task == 0x1234ULL && (__u64) comm == 0x5678ULL) {
 		on_cpu = bpf_get_smp_processor_id();
-		return (int)task + (int)comm;
+		return (long)task + (long)comm;
 	}
 
 	return 0;