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/efx.h b/drivers/net/sfc/efx.h
index e1e4488..060dc95 100644
--- a/drivers/net/sfc/efx.h
+++ b/drivers/net/sfc/efx.h
@@ -106,8 +106,9 @@
 
 static inline void efx_schedule_channel(struct efx_channel *channel)
 {
-	EFX_TRACE(channel->efx, "channel %d scheduling NAPI poll on CPU%d\n",
-		  channel->channel, raw_smp_processor_id());
+	netif_vdbg(channel->efx, intr, channel->efx->net_dev,
+		   "channel %d scheduling NAPI poll on CPU%d\n",
+		   channel->channel, raw_smp_processor_id());
 	channel->work_pending = true;
 
 	napi_schedule(&channel->napi_str);