macvtap add missing ioctls - fix wrapping

The macvtap driver tries to emulate all the ioctls supported by a normal
tun/tap driver, however it was missing the generic SIOCGIFHWADDR and
SIOCSIFHWADDR ioctls to get and set the mac address that are supported
by tun/tap. This patch adds these.

Signed-off-by: Justin Cormack <justin@netbsd.org>
Signed-off-by: David S. Miller <davem@davemloft.net>