[NET]: Add missing include to linux/netdevice.h

linux/etherdevice.h can't be included standalone at the moment, which
is required in order to sort the header files in the recommended
alphabetic order. This patch fixes that and is needed to build spider_net.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/etherdevice.h

···
 #define _LINUX_ETHERDEVICE_H
 
 #include <linux/if_ether.h>
+#include <linux/netdevice.h>
 #include <linux/random.h>
 
 #ifdef __KERNEL__