Fix VNIC module unloading

[wma]

Summary

Fix panics which were present when BGX and PF module were unloaded.

[zbb]

sys/dev/vnic/nic_main.c

247 ↗

(On Diff #16280)

Please add following code to the patch:

 static int
 nicpf_detach(device_t dev)
 {
 	struct nicpf *nic;
+	int err;
 
+	err = 0;
 	nic = device_get_softc(dev);
 
 	callout_drain(&nic->check_link);
 	mtx_destroy(&nic->check_link_mtx);
 
 	nic_unregister_interrupts(nic);
 	nicpf_free_res(nic);
 	pci_disable_busmaster(dev);
 
-	return (0);
+#ifdef PCI_IOV
+	err = pci_iov_detach(dev);
+	if (err != 0)
+		device_printf(dev, "SR-IOV in use. Detach first.\n");
+#endif
+	return (err);
 }