perf data: Close all files in close_dir()

perf data: Close all files in close_dir()

When using 'perf report' in directory mode, the first file is not closed
on exit, causing a memory leak.

The problem is caused by the iterating variable never reaching 0.

Fixes: faa8beb870fdcda9 ("perf data: Add perf_data__(create_dir|close_dir) functions")
Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Link: http://lore.kernel.org/lkml/20210716141122.858082-1-rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>