virtio-devices: Calculate number of msix interrupts in VirtioPciDevice

Rather than calculate in the DeviceManager and pass it through do it in
the device where it already has all the required information.

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

vmm/src/device_manager.rs

@@ -4172,11 +4172,6 @@ impl DeviceManager {
             return Err(DeviceManagerError::MissingNode);
         }
 
-        // Allows support for one MSI-X vector per interrupt needed by the device.
-        // It also adds 1 as we need to take into account the dedicated vector to notify
-        // about a virtio config change.
-        let msix_num = (virtio_device.lock().unwrap().queue_max_sizes().len() + 1) as u16;
-
         // Create the AccessPlatform trait from the implementation IommuMapping.
         // This will provide address translation for any virtio device sitting
         // behind a vIOMMU.
@@ -4245,7 +4240,6 @@ impl DeviceManager {
                 id.clone(),
                 memory,
                 virtio_device,
-                msix_num,
                 access_platform.as_ref(),
                 self.msi_interrupt_manager.as_ref(),
                 pci_device_bdf.into(),