appletalk: handle SIOCATALKDIFADDR compat ioctl

We must not have a compat ioctl handler for SIOCATALKDIFADDR
in common code, because the same number is used in other protocols
with different data structures.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>