Since Linux now supports CFI, it will be a good idea to fix mismatched
return type for implementation of hooks. Otherwise this might get
cought out by CFI and cause a panic.
bcm4908_enet_start_xmit() would return either NETDEV_TX_BUSY or
NETDEV_TX_OK, so change the return type to netdev_tx_t directly.
Signed-off-by: GUO Zihua <redacted>