virtio/wl: Fix build on linux-4.17+.

sys_close was removed and ksys_close should be used instead. See
2ca2a09d6215 for more details.

Change-Id: I64b4bb0cf6c027891ba9db70d2d24ed0a12a622b
diff --git a/drivers/virtio/virtio_wl.c b/drivers/virtio/virtio_wl.c
index ac8aff1..e4300ea 100644
--- a/drivers/virtio/virtio_wl.c
+++ b/drivers/virtio/virtio_wl.c
@@ -1183,7 +1183,7 @@ static long virtwl_ioctl_new(struct file *filp, void __user *ptr,
 	ret = copy_to_user(ptr, &ioctl_new, size);
 	if (ret) {
 		/* The release operation will handle freeing this alloc */
-		sys_close(ioctl_new.fd);
+		ksys_close(ioctl_new.fd);
 		return -EFAULT;
 	}