perf report/top: Make ENTER consistently bring up menu

When callchains are present the ENTER key switches from bringing up the
menu that offers Annotation, Zoom by DSO, etc to expanding/collapsing
one callchain level, causing confusion, fix it by making it consistently
bring up the menu and use '+' to expand/collapse one callchain level.

Next patch will also add an entry to the menu to allow
expanding/collapsing, so that people used to ENTER expanding one
callchain level can quickly find it and use it instead.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-bjz35omktig8cwn6lbj1ifns@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>