USB: usb-serial: fix the aircable_init failure path

The failure path of aircable_init is wrong, fix the order of (goto) labels.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: Naranjo Manuel Francisco <naranjo.manuel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>