perf hists browser: Fix the number of entries for 'e' key

perf hists browser: Fix the number of entries for 'e' key

The 'e' key is to toggle expand/collapse the selected entry only.  But
the current code has a bug that it only increases the number of entries
by 1 in the hierarchy mode so users cannot move under the current entry
after the key stroke.  This is due to a wrong assumption in the
hist_entry__set_folding().

The commit b33f922651011eff ("perf hists browser: Put hist_entry folding
logic into single function") factored out the code, but actually it
should be handled separately.  The hist_browser__set_folding() is to
update fold state for each entry so it needs to traverse all (child)
entries regardless of the current fold state.  So it increases the
number of entries by 1.

But the hist_entry__set_folding() only cares the currently selected
entry and its all children.  So it should count all unfolded child
entries.  This code is implemented in hist_browser__toggle_fold()
already so we can just call it.

Fixes: b33f922651011eff ("perf hists browser: Put hist_entry folding logic into single function")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230731094934.1616495-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>