perf annotate: Fix title line after return from call

The second title line which shows symbol and DSO name is broken after
moving to another function at 'callq' instruction.

The ui_browser__show_title() is used for the first line which shows
global sample count and event name so it doesn't change across the
functions.

What it needs after processing 'call' instruction is to update the
second line onlly.  Add a comment and call appropriate function.

You can verify the change by pressing ENTER on a 'call' instruction and
then ESC.

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: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>