perf annotate: Use al->data_nr if possible

perf annotate: Use al->data_nr if possible

The data_nr keeps the number of entries in al->data[] so it should use
it when it iterates the array.  The notes->src->nr_events should have
the same number but it'd be natural to use al->data_nr.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240803211332.1107222-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>