net: korina: fix return value

The ndo_start_xmit() method must not attempt to free the skb to transmit
when returning NETDEV_TX_BUSY. Therefore, make sure the
korina_send_packet() function returns NETDEV_TX_OK when it frees a packet.

Fixes: ef11291b

 ("Add support the Korina (IDT RC32434) Ethernet MAC")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201214220952.19935-1-vincent.stehle@laposte.net


Signed-off-by: Jakub Kicinski <kuba@kernel.org>