staging: octeon: Fix return type of cvm_oct_xmit and cvm_oct_xmit_pow

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 cvm_oct_xmit and cvm_oct_xmit_pow should be changed
from int to netdev_tx_t.

Link: https://github.com/ClangBuiltLinux/linux/issues/1703
Cc: llvm@lists.linux.dev
Reported-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Link: https://lore.kernel.org/r/20220914211057.423617-1-nhuck@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/octeon/ethernet-tx.c

@@ -125,7 +125,7 @@ static void cvm_oct_free_tx_skbs(struct net_device *dev)
  *
  * Returns Always returns NETDEV_TX_OK
  */
-int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
+netdev_tx_t cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	union cvmx_pko_command_word0 pko_command;
 	union cvmx_buf_ptr hw_buffer;
@@ -506,7 +506,7 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
  * @dev:    Device info structure
  * Returns Always returns zero
  */
-int cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
+netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev)
 {
 	struct octeon_ethernet *priv = netdev_priv(dev);
 	void *packet_buffer;

drivers/staging/octeon/ethernet-tx.h

@@ -5,8 +5,8 @@
  * Copyright (c) 2003-2007 Cavium Networks
  */
 
-int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev);
-int cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev);
+netdev_tx_t cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev);
+netdev_tx_t cvm_oct_xmit_pow(struct sk_buff *skb, struct net_device *dev);
 int cvm_oct_transmit_qos(struct net_device *dev, void *work_queue_entry,
 			 int do_free, int qos);
 void cvm_oct_tx_initialize(void);