perf evsel: Separate rlimit increase from evsel__open_cpu()

perf evsel: Separate rlimit increase from evsel__open_cpu()

This is a preparatory patch for the workqueue patches with the goal to
separate from evlist__open_cpu() the actual opening (which could be
performed in parallel), from the existing fallback mechanisms, which
should be handled sequentially.

This patch separates the rlimit increase from evsel__open_cpu().

Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/2f256de8ec37b9809a5cef73c2fa7bce416af5d3.1629490974.git.rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>