vmm: add NVIDIA GPUDirect P2P support

On platforms where PCIe P2P is supported, inject a PCI capability into
NVIDIA GPU to indicate support.

Signed-off-by: Thomas Barrett <tbarrett@crusoeenergy.com>

vmm/src/vm_config.rs

@@ -434,6 +434,8 @@ pub struct DeviceConfig {
     pub id: Option<String>,
     #[serde(default)]
     pub pci_segment: u16,
+    #[serde(default)]
+    pub x_nv_gpudirect_clique: Option<u8>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]