dvdnav: fix minor memory leak

This was usually handled at the end of the switch statement, so if
something returns from the function before that, the event has to be
freed explicitly.

player/dvdnav.c

@@ -166,6 +166,7 @@ void mp_handle_nav(struct MPContext *mpctx)
             MP_VERBOSE(nav, "reload\n");
             // return immediately.
             // other events should be handled after reloaded.
+            talloc_free(ev);
             return;
         }
         case MP_NAV_EVENT_RESET: {