OvmfPkg/Virtio10Dxe: convert to PciCapLib

Replace the manual capability list parsing in OvmfPkg/Virtio10Dxe with
PciCapLib and PciCapPciIoLib API calls.

The VIRTIO_PCI_CAP_LINK structure type is now superfluous. (Well, it
always has been; we should have used EFI_PCI_CAPABILITY_HDR.)

Also, EFI_PCI_CAPABILITY_VENDOR_HDR is now included at the front of
VIRTIO_PCI_CAP. No driver other than Virtio10Dxe relies on VIRTIO_PCI_CAP.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

OvmfPkg/Include/IndustryStandard/Virtio10.h

@@ -16,6 +16,7 @@
 #ifndef _VIRTIO_1_0_H_
 #define _VIRTIO_1_0_H_
 
+#include <IndustryStandard/Pci23.h>
 #include <IndustryStandard/Virtio095.h>
 
 //
@@ -29,11 +30,7 @@
 //
 #pragma pack (1)
 typedef struct {
-  UINT8 CapId;   // Capability identifier (generic)
-  UINT8 CapNext; // Link to next capability (generic)
-} VIRTIO_PCI_CAP_LINK;
-
-typedef struct {
+  EFI_PCI_CAPABILITY_VENDOR_HDR VendorHdr;
   UINT8  ConfigType; // Identifies the specific VirtIo 1.0 config structure
   UINT8  Bar;        // The BAR that contains the structure
   UINT8  Padding[3];