perf evsel: Separate missing feature disabling from evsel__open_cpu

perf evsel: Separate missing feature disabling from evsel__open_cpu

This is a preparatory patch for the patches in the workqueue series with
the goal to separate in 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 disabling of missing features from
evlist__open_cpu() into a new function evsel__disable_missing_features(().

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/48138bd2932646dde315505da733c2ca635ad2ee.1629490974.git.rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>