Some network devices - notably ipvlan slave - are not compatible with
any kind of rx_handler. Currently the hook can be installed but any
configuration (bridge, bond, macsec, ...) is nonfunctional.

This change allocates a priv_flag bit to mark such devices and explicitly
forbid installing a rx_handler if such bit is set. The new bit is used
by ipvlan slave device.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>