doc, net: Update netdev operation names

Commits d314774c ('netdev: network
device operations infrastructure') and
00829823

 ('netdev: add more functions
to netdevice ops') moved and renamed net device operation pointers.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>