MedPkg/Include: Add PCI_EXPRESS_EXTENDED_CAPABILITY_DVSEC_ID

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4515

Add PCI_EXPRESS_EXTENDED_CAPABILITY_DESIGNATED_VENDOR_SPECIFIC_ID
0x0023 in PciExpress40.h

Signed-off-by: Foster Nong <foster.nong@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdePkg/Include/IndustryStandard/PciExpress40.h

@@ -82,6 +82,8 @@ typedef struct {
 /// The Designated Vendor Specific Capability definitions
 /// Based on section 7.9.6 of PCI Express Base Specification 4.0.
 ///@{
+#define PCI_EXPRESS_EXTENDED_CAPABILITY_DESIGNATED_VENDOR_SPECIFIC_ID  0x0023
+
 typedef union {
   struct {
     UINT32    DvsecVendorId : 16;                                     // bit 0..15