mlx5, xsk: Diversify return values from xsk_wakeup call paths

Currently, when debugging AF_XDP workloads, one can correlate the -ENXIO
return code as the case that XSK is not in the bound state. Returning
same code from ndo_xsk_wakeup can be misleading and simply makes it
harder to follow what is going on.

Change ENXIO in mlx5's ndo_xsk_wakeup() implementation to EINVAL, so
that when probing it is clear that something is wrong on the driver
side, not the xsk_{recv,send}msg.

There is a -ENETDOWN that can happen from both kernel/driver sides
though, but I don't have a correct replacement for this on one of the
sides, so let's keep it that way.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220413153015.453864-12-maciej.fijalkowski@intel.com

drivers/net/ethernet/mellanox/mlx5/core/en/xsk/tx.c

@@ -23,7 +23,7 @@ int mlx5e_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags)
 	c = priv->channels.c[ix];
 
 	if (unlikely(!test_bit(MLX5E_CHANNEL_STATE_XSK, c->state)))
-		return -ENXIO;
+		return -EINVAL;
 
 	if (!napi_if_scheduled_mark_missed(&c->napi)) {
 		/* To avoid WQE overrun, don't post a NOP if async_icosq is not