net: enetc: allow tc-etf offload even with NETIF_F_CSUM_MASK

The Time-Specified Departure feature is indeed mutually exclusive with
TX IP checksumming in ENETC, but TX checksumming in itself is broken and
was removed from this driver in commit 82728b9 ("enetc: Remove Tx
checksumming offload code").

The blamed commit declared NETIF_F_HW_CSUM in dev->features to comply
with software TSO's expectations, and still did the checksumming in
software by calling skb_checksum_help(). So there isn't any restriction
for the Time-Specified Departure feature.

However, enetc_setup_tc_txtime() doesn't understand that, and blindly
looks for NETIF_F_CSUM_MASK.

Instead of checking for things which can literally never happen in the
current code base, just remove the check and let the driver offload
tc-etf qdiscs.

Fixes: acede3c ("net: enetc: declare NETIF_F_HW_CSUM and do it in software")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220427203017.1291634-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: vladimiroltean

drivers/net/ethernet/freescale/enetc/enetc_qos.c

@@ -297,10 +297,6 @@ int enetc_setup_tc_txtime(struct net_device *ndev, void *type_data)
 	if (tc < 0 || tc >= priv->num_tx_rings)
 		return -EINVAL;
 
-	/* Do not support TXSTART and TX CSUM offload simutaniously */
-	if (ndev->features & NETIF_F_CSUM_MASK)
-		return -EBUSY;
-
 	/* TSD and Qbv are mutually exclusive in hardware */
 	if (enetc_rd(&priv->si->hw, ENETC_QBV_PTGCR_OFFSET) & ENETC_QBV_TGE)
 		return -EBUSY;