perf hists browser: The dso can be obtained from popup_action->ms.map->dso

So no need to have a 'dso' member in 'popup_action', remove it as no
code is using it, already.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/ui/browsers/hists.c

···
 
 struct popup_action {
 	struct thread 		*thread;
-	struct dso		*dso;
 	struct map_symbol 	ms;
 	int			socket;
 
···
 		return 0;
 
 	act->ms.map = map;
-	act->dso = map->dso;
 	act->fn = do_zoom_dso;
 	return 1;
 }
···
 
 	while (1) {
 		struct thread *thread = NULL;
-		struct dso *dso = NULL;
 		struct map *map = NULL;
 		int choice = 0;
 		int socked_id = -1;
···
 		if (browser->he_selection != NULL) {
 			thread = hist_browser__selected_thread(browser);
 			map = browser->selection->map;
-			if (map)
-				dso = map->dso;
 			socked_id = browser->he_selection->socket;
 		}
 		switch (key) {
···
 			hist_browser__dump(browser);
 			continue;
 		case 'd':
-			actions->dso = dso;
 			actions->ms.map = map;
 			do_zoom_dso(browser, actions);
 			continue;