freebsd_network: Move up Giant ownership during attach.

device_attach can be recursed for MIIbus drivers, so avoid the complexity
and lock Giant from init_drivers() instead.

src/libs/compat/freebsd_network/device.c

@@ -481,9 +481,6 @@ device_attach(device_t device)
 		|| device->methods.attach == NULL)
 		return B_ERROR;
 
-	// Always hold the giant lock during attach.
-	mtx_lock(&Giant);
-
 	result = device->methods.attach(device);
 
 	if (result == 0)
@@ -492,7 +489,6 @@ device_attach(device_t device)
 	if (result == 0 && HAIKU_DRIVER_REQUIRES(FBSD_WLAN_FEATURE))
 		result = start_wlan(device);
 
-	mtx_unlock(&Giant);
 	return result;
 }
 

src/libs/compat/freebsd_network/driver.c

@@ -310,6 +310,9 @@ _fbsd_init_drivers()
 	if (status < B_OK)
 		goto err6;
 
+	// Always hold the giant lock during attach.
+	mtx_lock(&Giant);
+
 	for (int p = 0; sProbedDevices[p].bus != BUS_INVALID; p++) {
 		device_t root, device = NULL;
 		status = init_root_device(&root, sProbedDevices[p].bus);
@@ -341,6 +344,8 @@ _fbsd_init_drivers()
 			device_delete_child(NULL, root);
 	}
 
+	mtx_unlock(&Giant);
+
 	if (gDeviceCount > 0)
 		return B_OK;