sfc: only use RSS filters if we're using RSS

Without this, filter insertion on a VF would fail if only one channel
was in use. This would include the unicast station filter and therefore
no traffic would be received.

Signed-off-by: Bert Kenward <bkenward@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
index 5a1c5a8..133e9e3 100644
--- a/drivers/net/ethernet/sfc/farch.c
+++ b/drivers/net/ethernet/sfc/farch.c
@@ -2242,7 +2242,7 @@
 	 */
 	spec->priority = EFX_FILTER_PRI_AUTO;
 	spec->flags = (EFX_FILTER_FLAG_RX |
-		       (efx->n_rx_channels > 1 ? EFX_FILTER_FLAG_RX_RSS : 0) |
+		       (efx_rss_enabled(efx) ? EFX_FILTER_FLAG_RX_RSS : 0) |
 		       (efx->rx_scatter ? EFX_FILTER_FLAG_RX_SCATTER : 0));
 	spec->dmaq_id = 0;
 }