vmm: config: Switch FsConfig to use PciDeviceCommonConfig

Switch FsConfig over to using the newly extracted struct members as used
by all PCI based devices. The use of #[serde(flatten)] means that this
change has no impact on the JSON format that the data is stored as.

As virtio-fs does not support being placed behind an IOMMU an error is
now raised if iommu is set. This option is not exposed via the CLI but
could happen with a miscontructed JSON/API call.

Signed-off-by: Rob Bradford <rbradford@meta.com>

vmm/src/vm_config.rs

@@ -471,16 +471,14 @@ pub struct PvmemcontrolConfig {}
 
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]
 pub struct FsConfig {
+    #[serde(flatten)]
+    pub pci_common: PciDeviceCommonConfig,
     pub tag: String,
     pub socket: PathBuf,
     #[serde(default = "default_fsconfig_num_queues")]
     pub num_queues: usize,
     #[serde(default = "default_fsconfig_queue_size")]
     pub queue_size: u16,
-    #[serde(default)]
-    pub id: Option<String>,
-    #[serde(default)]
-    pub pci_segment: u16,
 }
 
 pub fn default_fsconfig_num_queues() -> usize {