[TUNTAP]: Allow setting the linktype of the tap device from userspace
Currently tun/tap only supports the EN10MB ARP type. For use with
wireless and other networking types it should be possible to set the
ARP type via an ioctl.
Patch v2: Included check that the tap interface is down before changing the
link type out from underneath it
Signed-off-by: Mike Kershaw <dragorn@kismetwireless.net> Signed-off-by: David S. Miller <davem@davemloft.net>