net: bonding: move ioctl handling to private ndo operation

All other user triggered operations are gone from ndo_ioctl, so move
the SIOCBOND family into a custom operation as well.

The .ndo_ioctl() helper is no longer called by the dev_ioctl.c code now,
but there are still a few definitions in obsolete wireless drivers as well
as the appletalk and ieee802154 layers to call SIOCSIFADDR/SIOCGIFADDR
helpers from inside the kernel.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>