perf test: Fix offcpu test prev_state check

On Fedora 36, the 'perf record' offcpu profiling tests are failing.  It

was because the BPF checks the prev task's state being S or D but
actually it has more bits set.  Let's check the LSB 8 bits for the
purpose of offcpu profiling.
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230218162724.1292657-1-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf_skel/off_cpu.bpf.c

@@ -277,7 +277,7 @@ int on_switch(u64 *ctx)
 	else
 		prev_state = get_task_state(prev);
 
-	return off_cpu_stat(ctx, prev, next, prev_state);
+	return off_cpu_stat(ctx, prev, next, prev_state & 0xff);
 }
 
 char LICENSE[] SEC("license") = "Dual BSD/GPL";