MdePkg/MdeModulePkg: Move AML_NAME_SEG_SIZE definition

A NameSeg is made 4 chars.
Cf. ACPI 6.4 s20.2.2 "Name Objects Encoding":
NameSeg := <leadnamechar namechar namechar namechar>
Notice that NameSegs shorter than 4 characters are filled
with trailing underscores (‘_’s).

AML_NAME_SEG_SIZE is currently defined in:
- DynamicTablesPkg/Library/Common/AmlLib/AmlDefines.h
- MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h
Since the value can be inferred from the ACPI specification
and to avoid multiple definitions, move it to
MdePkg/Include/IndustryStandard/

Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

MdeModulePkg/Universal/Acpi/AcpiTableDxe/AcpiSdt.h

@@ -56,7 +56,6 @@ typedef struct _EFI_AML_NODE_LIST EFI_AML_NODE_LIST;
 //  Size is the total size of this ACPI node buffer.
 //  Children is the children linked list of this node.
 //
-#define AML_NAME_SEG_SIZE  4
 
 struct _EFI_AML_NODE_LIST {
   UINT32                  Signature;

MdePkg/Include/IndustryStandard/AcpiAml.h

@@ -2,7 +2,7 @@
   This file contains AML code definition in the latest ACPI spec.
 
   Copyright (c) 2011, Intel Corporation. All rights reserved.<BR>
-  Copyright (c) 2019, ARM Limited. All rights reserved.<BR>
+  Copyright (c) 2019 - 2021, Arm Limited. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -176,4 +176,9 @@
 #define AML_FIELD_CONNECTION_OP      0x02
 #define AML_FIELD_EXT_ACCESS_OP      0x03
 
+//
+// AML Name segment definitions
+//
+#define AML_NAME_SEG_SIZE            4
+
 #endif