perf evsel: Move bpf_counter__install_pe() to success path in evsel__open_cpu()

I don't see why bpf_counter__install_pe() should get called even if
fd = -1, so I'm moving it to the success path.

This will be useful in following patches to separate the actual open and
the related operations from the fallback mechanisms.

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>
Cc: Song Liu <songliubraving@fb.com>
Link: http://lore.kernel.org/lkml/64f8a1b0a838a6e6049cd43c1beafd432999ae57.1629490974.git.rickyman7@gmail.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>