infiniband: remove dev_base_lock use

dev_base_lock is the legacy way to lock the device list, and is planned
to disappear. (writers hold RTNL, readers hold RCU lock)

Convert rdma_translate_ip() and update_ipv6_gids() to RCU locking.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>