ACPI: disable ACPI cleanly when bad RSDP found

When ACPI is disabled in the BIOS of this VIA C3 box,
it invalidates the RSDP, which Linux notices:

ACPI Error (tbxfroot-0218): A valid RSDP was not found [20080926]

Bug Linux neglected to disable ACPI at that stage,
and later scribbled on smp_found_config:

ACPI: No APIC-table, disabling MPS

But this box doesn't run well in legacy PIC mode,
it needed IOAPIC mode to perform correctly:

http://lkml.org/lkml/2009/2/5/39

So exit ACPI mode cleanly when we first detect
that it is hopeless.
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/tables.c

@@ -293,7 +293,12 @@ static void __init check_multiple_madt(void)
 
 int __init acpi_table_init(void)
 {
-	acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
+	acpi_status status;
+
+	status = acpi_initialize_tables(initial_tables, ACPI_MAX_TABLES, 0);
+	if (ACPI_FAILURE(status))
+		return 1;
+
 	check_multiple_madt();
 	return 0;
 }