ipvlan: selects master_l3 device instead of depending on it

The L3 Master device is just a glue between the core networking code and
device drivers, so it should be selected automatically rather than
requiring to be enabled explicitly.

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>