The current implementation of dev_ifname makes maintenance difficult
because updates to the implementation of the ioctl have to made in two
places.  So this patch updates dev_ifname32 to do a classic 32/64
structure conversion and call sys_ioctl like the rest of the
compat calls do.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>