MdePkg: Acpi66: Add defined IOVT Signature

ACPI 6.6 introduced new Virtualization Table for LoongArch.
This follow-up will provide configuration for IOMMU.

REF: https://uefi.org/sites/default/files/resources/ACPI_Spec_6.6.pdf
Table5.6: “IOVT” I/O Virtualization Table.

Reported-by: Xianglai Li <[email protected]>
Signed-off-by: Dongyan Qian <[email protected]>

Author: MarsDoge

MdePkg/Include/IndustryStandard/Acpi66.h

@@ -3424,6 +3424,11 @@ typedef struct {
 ///
 #define EFI_ACPI_6_6_IO_REMAPPING_TABLE_SIGNATURE  SIGNATURE_32('I', 'O', 'R', 'T')
 
+///
+/// "IOVT" I/O Virtualization Table
+///
+#define EFI_ACPI_6_6_IO_VIRTUALIZATION_TABLE_SIGNATURE  SIGNATURE_32('I', 'O', 'V', 'T')
+
 ///
 /// "IVRS" I/O Virtualization Reporting Structure
 ///