Callchains are automatically initialized by checking on event's
sample_type. For pipe mode we need to put this check into attr event
code.

Moving the callchains setup code into callchain_param_setup function and
calling it from attr event process code.

This enables pipe output having callchains, like:

  # perf record -g -e 'raw_syscalls:sys_enter' true | perf script
  # perf record -g -e 'raw_syscalls:sys_enter' true | perf report

Committer notes:

We still need the next patch for the above output to work.
Reported-by: Paul Khuong <pvk@pvk.ca>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200507095024.2789147-5-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>