network/netdev: introduce .iftype to netdev vtable

And disable .generate_mac flag for non-ether interfaces.

src/network/netdev/netdevsim.c

@@ -1,10 +1,13 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <linux/if_arp.h>
+
 #include "netdevsim.h"
 
 const NetDevVTable netdevsim_vtable = {
         .object_size = sizeof(NetDevSim),
         .sections = NETDEV_COMMON_SECTIONS,
         .create_type = NETDEV_CREATE_INDEPENDENT,
+        .iftype = ARPHRD_ETHER,
         .generate_mac = true,
 };