perf off_cpu: Fix a typo in BTF tracepoint name, it should be 'btf_trace_sched_switch'

In BTF, tracepoint definitions have the "btf_trace_" prefix.  The
off-cpu profiler needs to check the signature of the sched_switch event
using that definition.  But there's a typo (s/bpf/btf/) so it failed
always.

Fixes: b36888f7 ("perf record: Handle argument change in sched_switch")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: bpf@vger.kernel.org
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20221208182636.524139-1-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/bpf_off_cpu.c

@@ -102,7 +102,7 @@ static void check_sched_switch_args(void)
 	const struct btf_type *t1, *t2, *t3;
 	u32 type_id;
 
-	type_id = btf__find_by_name_kind(btf, "bpf_trace_sched_switch",
+	type_id = btf__find_by_name_kind(btf, "btf_trace_sched_switch",
 					 BTF_KIND_TYPEDEF);
 	if ((s32)type_id < 0)
 		return;