nconfig: Fix help for choice menus

When getting the help for a choice menu with a help section (for example
the "Choose SLAB allocator" menu) nconfig pops up a window with nothing
inside it. This is due to show_help() passing an empty string to
show_scroll_win()'s 3rd argument. The option really does have help
though, but it isn't a config symbol, so just add the help text for
the option, and don't try to add anything else like the config option
name.

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Acked-by: Nir Tzachar <nir.tzachar@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/kconfig/nconf.c

@@ -1265,6 +1265,8 @@ static void show_help(struct menu *menu)
 			str_append(&help, _(menu_get_help(menu)));
 			str_append(&help, "\n");
 			get_symbol_str(&help, menu->sym);
+		} else {
+			str_append(&help, _(menu_get_help(menu)));
 		}
 	} else {
 		str_append(&help, nohelp_text);