OvmfPkg/VirtioGpuDxe: query native display resolution from host

Try query native display resolution from the host.  When successful,
setup PcdVideoHorizontalResolution and PcdVideoVerticalResolution
accordingly and add the video mode to the GOP mode list if needed.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

OvmfPkg/VirtioGpuDxe/VirtioGpu.h

@@ -151,6 +151,12 @@ struct VGPU_GOP_STRUCT {
   // BackingStore is non-NULL.
   //
   VOID                                    *BackingStoreMap;
+
+  //
+  // native display resolution
+  //
+  UINT32                                  NativeXRes;
+  UINT32                                  NativeYRes;
 };
 
 //