amd-xgbe: Check for Tx hardware queue flushing support

The flushing of the Tx hardware queues is only supported at a certain
level of the hardware.  Retrieve the current version of the hardware
and use that to determine if flushing is supported.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index edaca44..e43747a 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -1633,6 +1633,9 @@
 {
 	unsigned int i, count;
 
+	if (XGMAC_GET_BITS(pdata->hw_feat.version, MAC_VR, SNPSVER) < 0x21)
+		return 0;
+
 	for (i = 0; i < pdata->tx_q_count; i++)
 		XGMAC_MTL_IOWRITE_BITS(pdata, i, MTL_Q_TQOMR, FTQ, 1);