net: consolidate and fix ethtool_ops->get_settings calling

This patch does several things:
- introduces __ethtool_get_settings which is called from ethtool code and
  from drivers as well. Put ASSERT_RTNL there.
- dev_ethtool_get_settings() is replaced by __ethtool_get_settings()
- changes calling in drivers so rtnl locking is respected. In
  iboe_get_rate was previously ->get_settings() called unlocked. This
  fixes it. Also prb_calc_retire_blk_tmo() in af_packet.c had the same
  problem. Also fixed by calling __dev_get_by_index() instead of
  dev_get_by_index() and holding rtnl_lock for both calls.
- introduces rtnl_lock in bnx2fc_vport_create() and fcoe_vport_create()
  so bnx2fc_if_create() and fcoe_if_create() are called locked as they
  are from other places.
- use __ethtool_get_settings() in bonding code

Signed-off-by: Jiri Pirko <jpirko@redhat.com>

v2->v3:
	-removed dev_ethtool_get_settings()
	-added ASSERT_RTNL into __ethtool_get_settings()
	-prb_calc_retire_blk_tmo - use __dev_get_by_index() and lock
	 around it and __ethtool_get_settings() call
v1->v2:
        add missing export_symbol
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com> [except FCoE bits]
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_if.c

@@ -35,7 +35,7 @@ static int port_cost(struct net_device *dev)
 {
 	struct ethtool_cmd ecmd;
 
-	if (!dev_ethtool_get_settings(dev, &ecmd)) {
+	if (!__ethtool_get_settings(dev, &ecmd)) {
 		switch (ethtool_cmd_speed(&ecmd)) {
 		case SPEED_10000:
 			return 2;