sfc: don't report RX hash keys to ethtool when RSS wasn't enabled

If we failed to set up RSS on EF10 (e.g. because firmware declared
 RX_RSS_LIMITED), ethtool --show-nfc $dev rx-flow-hash ... should report
 no fields, rather than confusingly reporting what fields we _would_ be
 hashing on if RSS was working.

Fixes: dcb4123cbe ("sfc: disable RSS when unsupported")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/sfc/siena.c

@@ -403,6 +403,7 @@ static int siena_init_nic(struct efx_nic *efx)
 	efx_writeo(efx, &temp, FR_AZ_RX_CFG);
 
 	siena_rx_push_rss_config(efx, false, efx->rx_indir_table);
+	efx->rss_active = true;
 
 	/* Enable event logging */
 	rc = efx_mcdi_log_ctrl(efx, true, false, 0);