kconfig: remove sym from struct property

struct property can reference to the symbol that it is associated with
by prop->menu->sym.

Fix up the one usage of prop->sym, and remove sym from struct property.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/parser.y

@@ -660,7 +660,7 @@ static void print_symbol(FILE *out, struct menu *menu)
 			break;
 		case P_SYMBOL:
 			fputs( "  symbol ", out);
-			fprintf(out, "%s\n", prop->sym->name);
+			fprintf(out, "%s\n", prop->menu->sym->name);
 			break;
 		default:
 			fprintf(out, "  unknown prop %d!\n", prop->type);