ACPICA: Add support for MADT online enabled bit

The online enabled bit on newer ACPI implmentations will indicate
whether the CPU is hotpluggable.

Link: http://github.com/acpica/acpica/pull/708/
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/acpi/actbl2.h

@@ -978,6 +978,7 @@ struct acpi_madt_multiproc_wakeup_mailbox {
 /* MADT Local APIC flags */
 
 #define ACPI_MADT_ENABLED           (1)	/* 00: Processor is usable if set */
+#define ACPI_MADT_ONLINE_CAPABLE    (2)	/* 01: System HW supports enabling processor at runtime */
 
 /* MADT MPS INTI flags (inti_flags) */