MdePkg /IoRemappingTable: Define additional IORT SMMUv3 node flags.

The flag for HTTU override in an SMMUv3 node in the IORT table is
defined in MdePkg/Include/IndustryStandard/IoRemappingTable.h as
a single bit. BIT0 or BIT1. The implementation of this field is
actually two bits, with the following mapings:

0b0000: Hardware update of the Access flag and dirty state are not
supported.
0b0001: Support for hardware update of the Access flag for Block and
Page descriptors.
0b0010: As 0b0001, and adds support for hardware update of the Access
flag for Block and Page descriptors. Hardware update of dirty state is
supported.

Referenced in Arm® System Memory Management Unit Architecture Specification
SMMU architecture version 3:
https://documentation-service.arm.com/static/63d7a2d5e4378a55c5e045b9

Signed-off-by: Aaron Pop <[email protected]>

MdePkg/Include/IndustryStandard/IoRemappingTable.h

@@ -61,7 +61,8 @@
 #define EFI_ACPI_IORT_SMMUv1v2_INT_FLAG_EDGE   0x1
 
 #define EFI_ACPI_IORT_SMMUv3_FLAG_COHAC_OVERRIDE    BIT0
-#define EFI_ACPI_IORT_SMMUv3_FLAG_HTTU_OVERRIDE     BIT1
+#define EFI_ACPI_IORT_SMMUv3_FLAG_HTTU_OVERRIDE     BIT1  // HW update of Access Flag supported
+#define EFI_ACPI_IORT_SMMUv3_FLAG_HTTU_OVERRIDE_DS  BIT2  // HW update of Access Flag + Dirty Flag supported
 #define EFI_ACPI_IORT_SMMUv3_FLAG_PROXIMITY_DOMAIN  BIT3
 #define EFI_ACPI_IORT_SMMUv3_FLAG_DEVICEID_VALID    BIT4