fix test_attach_legacy_devices

A KVM patch added a new validation when using the KVM_IRQFD ioctl. This
breaks our test_attach_legacy_devices unit test. We can fix it by
calling setup_interrupt_controller() before attaching the legacy
devices.

Signed-off-by: Serban Iorga <[email protected]>

Author: Serban Iorga

vmm/src/lib.rs

@@ -3238,6 +3238,8 @@ mod tests {
     #[test]
     fn test_attach_legacy_devices() {
         let mut vmm = create_vmm_object(InstanceState::Uninitialized);
+        vmm.setup_interrupt_controller()
+            .expect("Failed to setup interrupt controller");
 
         assert!(vmm.attach_legacy_devices().is_ok());
         assert!(vmm.legacy_device_manager.io_bus.get_device(0x3f8).is_some());