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>

drivers/net/ethernet/sfc/efx.h

@@ -76,6 +76,11 @@ void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
 #define EFX_TXQ_MAX_ENT(efx)	(EFX_WORKAROUND_35388(efx) ? \
 				 EFX_MAX_DMAQ_SIZE / 2 : EFX_MAX_DMAQ_SIZE)
 
+static inline bool efx_rss_enabled(struct efx_nic *efx)
+{
+	return efx->rss_spread > 1;
+}
+
 /* Filters */
 
 void efx_mac_reconfigure(struct efx_nic *efx);