MdePkg: MADT: Add Online capable flag in GICC

Bugzilla: 3706 'Code First - MADT GICC new flags'

On ARM systems physical CPU hotplug is not supported.
All CPUs are considered present and this is true
throughout the system uptime.

The ECR 2285 introduces a new 'online-capable' flag
in the GICC structure flags in ACPI 6.5, to signal
firmware policy (CPU is not enabled but it can be
enabled and onlined). This enables OSPM to support
virtual CPU hotplug (on virtual platforms for
instance).

This ECR also updates the MADT table revision to 6
to reflect the ACPI 6.5 changes. Therefore, update
the MADT table revision to match the value as
specified in ACPI 6.5.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Pierre Gondois  <pierre.gondois@arm.com>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>

MdePkg/Include/IndustryStandard/Acpi65.h

@@ -2,7 +2,7 @@
   ACPI 6.5 definitions from the ACPI Specification Revision 6.5 Aug, 2022.
 
   Copyright (c) 2017 - 2022, Intel Corporation. All rights reserved.<BR>
-  Copyright (c) 2019 - 2021, ARM Ltd. All rights reserved.<BR>
+  Copyright (c) 2019 - 2023, ARM Ltd. All rights reserved.<BR>
   Copyright (c) 2023, Loongson Technology Corporation Limited. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
@@ -533,6 +533,7 @@ typedef struct {
 #define EFI_ACPI_6_5_GIC_ENABLED                            BIT0
 #define EFI_ACPI_6_5_PERFORMANCE_INTERRUPT_MODEL            BIT1
 #define EFI_ACPI_6_5_VGIC_MAINTENANCE_INTERRUPT_MODE_FLAGS  BIT2
+#define EFI_ACPI_6_5_GIC_ONLINE_CAPABLE                     BIT3
 
 ///
 /// GIC Distributor Structure