ixgbe: Avoid to write the RETA table when unnecessary

If indir == 0 in the ixgbe_set_rxfh(), it is unnecessary
to write the HW. Because redirection table is not changed.
Signed-off-by: NTonghao Zhang <xiangxia.m.yue@gmail.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c

@@ -3059,6 +3059,8 @@ static int ixgbe_set_rxfh(struct net_device *netdev, const u32 *indir,
 
 		for (i = 0; i < reta_entries; i++)
 			adapter->rss_indir_tbl[i] = indir[i];
+
+		ixgbe_store_reta(adapter);
 	}
 
 	/* Fill out the rss hash key */
@@ -3067,8 +3069,6 @@ static int ixgbe_set_rxfh(struct net_device *netdev, const u32 *indir,
 		ixgbe_store_key(adapter);
 	}
 
-	ixgbe_store_reta(adapter);
-
 	return 0;
 }