net: ethernet: ti: davinci_emac: Fix return type of emac_dev_xmit

The ndo_start_xmit field in net_device_ops is expected to be of type
netdev_tx_t (*ndo_start_xmit)(struct sk_buff *skb, struct net_device *dev).

The mismatched return type breaks forward edge kCFI since the underlying
function definition does not match the function hook definition.

The return type of emac_dev_xmit should be changed from int to
netdev_tx_t.

Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1703
Cc: llvm@lists.linux.dev
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20220912195023.810319-1-nhuck@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/davinci_emac.c

@@ -949,7 +949,7 @@ static void emac_tx_handler(void *token, int len, int status)
  *
  * Returns success(NETDEV_TX_OK) or error code (typically out of desc's)
  */
-static int emac_dev_xmit(struct sk_buff *skb, struct net_device *ndev)
+static netdev_tx_t emac_dev_xmit(struct sk_buff *skb, struct net_device *ndev)
 {
 	struct device *emac_dev = &ndev->dev;
 	int ret_code;