net: toshiba: fix return type of ndo_start_xmit function

net: toshiba: fix return type of ndo_start_xmit function

BugLink: https://bugs.launchpad.net/bugs/1853915
[ Upstream commit bacade822524e02f662d88f784d2ae821a5546fb ]

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, so make sure the implementation in
this driver has returns 'netdev_tx_t' value, and change the function
return type to netdev_tx_t.

Found by coccinelle.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>