can: etas_es58x: es58x_init_netdev(): free netdev when register_candev()

In case of register_candev() fails, clear
es58x_dev->netdev[channel_idx] and add free_candev(). Otherwise
es58x_free_netdevs() will unregister the netdev that has never been
registered.

Fixes: 85372578

 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Acked-by: Arunachalam Santhanam <Arunachalam.Santhanam@in.bosch.com>
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/1668413685-23354-1-git-send-email-zhangchangzhong@huawei.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>