perf/bpf: Mark perf_event_set_bpf_handler() and perf_event_free_bpf_handler() as inline too

They can be unused with certain Kconfig variations:

  kernel/events/core.c:9622:13: warning: ‘perf_event_free_bpf_handler’ defined but not used [-Wunused-function]
  kernel/events/core.c:9586:12: warning: ‘perf_event_set_bpf_handler’ defined but not used [-Wunused-function]

Since they are both single-use, mark them inline.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Kyle Huey <khuey@kylehuey.com>

kernel/events/core.c

@@ -9583,9 +9583,9 @@ static int bpf_overflow_handler(struct perf_event *event,
 	return ret;
 }
 
-static int perf_event_set_bpf_handler(struct perf_event *event,
-				      struct bpf_prog *prog,
-				      u64 bpf_cookie)
+static inline int perf_event_set_bpf_handler(struct perf_event *event,
+					     struct bpf_prog *prog,
+					     u64 bpf_cookie)
 {
 	if (event->overflow_handler_context)
 		/* hw breakpoint or kernel counter */
@@ -9619,7 +9619,7 @@ static int perf_event_set_bpf_handler(struct perf_event *event,
 	return 0;
 }
 
-static void perf_event_free_bpf_handler(struct perf_event *event)
+static inline void perf_event_free_bpf_handler(struct perf_event *event)
 {
 	struct bpf_prog *prog = event->prog;