net: move ndo_features_check() close to ndo_start_xmit()

TX fast path uses ndo_start_xmit(), ndo_features_check() and
ndo_select_queue().

Move ndo_features_check() close to ndo_start_xmit() to increase
data locality.

All "struct net_device_ops" should now be using C99 initializers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>