tracing: Allow perf to read synthetic events

tracing: Allow perf to read synthetic events

Currently, perf can not enable synthetic events. When it does, it either
causes a warning in the kernel or errors with "no such device".

Add the necessary code to allow perf to also attach to synthetic events.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260513150007.3b280e87@gandalf.local.home
Reported-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>