Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: ca139d76 ("cx82310_eth: re-enable ethernet mode after router reboot")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Link: https://lore.kernel.org/r/1605247627-15385-1-git-send-email-zhangchangzhong@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>