sfc: Implement message level control

Replace EFX_ERR() with netif_err(), EFX_INFO() with netif_info(),
EFX_LOG() with netif_dbg() and EFX_TRACE() and EFX_REGDUMP() with
netif_vdbg().

Replace EFX_ERR_RL(), EFX_INFO_RL() and EFX_LOG_RL() using explicit
calls to net_ratelimit().

Implement the ethtool operations to get and set message level flags,
and add a 'debug' module parameter for the initial value.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/mdio_10g.h b/drivers/net/sfc/mdio_10g.h
index f89e719..75791d3 100644
--- a/drivers/net/sfc/mdio_10g.h
+++ b/drivers/net/sfc/mdio_10g.h
@@ -51,7 +51,8 @@
 
 	sync = !!(lane_status & MDIO_PHYXS_LNSTAT_ALIGN);
 	if (!sync)
-		EFX_LOG(efx, "XGXS lane status: %x\n", lane_status);
+		netif_dbg(efx, hw, efx->net_dev, "XGXS lane status: %x\n",
+			  lane_status);
 	return sync;
 }