net: stmmac: xgmac: Fix TSA selection

When we change between Transmission Scheduling Algorithms, we need to
clear previous values so that the new chosen algorithm is correctly
selected.

Fixes: ec6ea8e3 ("net: stmmac: Add CBS support in XGMAC2")
Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c

@@ -224,6 +224,7 @@ static void dwxgmac2_config_cbs(struct mac_device_info *hw,
 	writel(low_credit, ioaddr + XGMAC_MTL_TCx_LOCREDIT(queue));
 
 	value = readl(ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(queue));
+	value &= ~XGMAC_TSA;
 	value |= XGMAC_CC | XGMAC_CBS;
 	writel(value, ioaddr + XGMAC_MTL_TCx_ETS_CONTROL(queue));
 }