net: stmmac: fix up RX flow hash indirection table when setting channels

stmmac_reinit_queues() fails to fix up the RX hash.  Even if the number
of channels gets restricted, the output of `ethtool -x' indicates that
all RX queues are used:

  $ ethtool -l enp0s29f2
  Channel parameters for enp0s29f2:
  Pre-set maximums:
  RX:		8
  TX:		8
  Other:		n/a
  Combined:	n/a
  Current hardware settings:
  RX:		8
  TX:		8
  Other:		n/a
  Combined:	n/a
  $ ethtool -x enp0s29f2
  RX flow hash indirection table for enp0s29f2 with 8 RX ring(s):
      0:      0     1     2     3     4     5     6     7
      8:      0     1     2     3     4     5     6     7
  [...]
  $ ethtool -L enp0s29f2 rx 3
  $ ethtool -x enp0s29f2
  RX flow hash indirection table for enp0s29f2 with 3 RX ring(s):
      0:      0     1     2     3     4     5     6     7
      8:      0     1     2     3     4     5     6     7
  [...]

Fix this by setting the indirection table according to the number
of specified queues.  The result is now as expected:

  $ ethtool -L enp0s29f2 rx 3
  $ ethtool -x enp0s29f2
  RX flow hash indirection table for enp0s29f2 with 3 RX ring(s):
      0:      0     1     2     0     1     2     0     1
      8:      2     0     1     2     0     1     2     0
  [...]

Tested on Intel Elkhart Lake.

Fixes: 0366f7e0 ("net: stmmac: add ethtool support for get/set channels")
Signed-off-by: Corinna Vinschen <vinschen@redhat.com>
Link: https://lore.kernel.org/r/20230403121120.489138-1-vinschen@redhat.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -6950,7 +6950,7 @@ static void stmmac_napi_del(struct net_device *dev)
 int stmmac_reinit_queues(struct net_device *dev, u32 rx_cnt, u32 tx_cnt)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
-	int ret = 0;
+	int ret = 0, i;
 
 	if (netif_running(dev))
 		stmmac_release(dev);
@@ -6959,6 +6959,10 @@ int stmmac_reinit_queues(struct net_device *dev, u32 rx_cnt, u32 tx_cnt)
 
 	priv->plat->rx_queues_to_use = rx_cnt;
 	priv->plat->tx_queues_to_use = tx_cnt;
+	if (!netif_is_rxfh_configured(dev))
+		for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
+			priv->rss.table[i] = ethtool_rxfh_indir_default(i,
+									rx_cnt);
 
 	stmmac_napi_add(dev);