perf ftrace: system_wide collection is not effective by default

perf ftrace: system_wide collection is not effective by default

The ftrace.target.system_wide must be set before invoking
evlist__create_maps(), otherwise it has no effect.

Fixes: 53be50282269b46c ("perf ftrace: Add 'latency' subcommand")
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220127132010.4836-1-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>