staging: fwserial: Fix error handling in fwserial_create

When fw_core_add_address_handler() fails, we need to destroy
the port by tty_port_destroy(). Also we need to unregister
the address handler by fw_core_remove_address_handler() on
failure.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/r/20201221122437.10274-1-dinghao.liu@zju.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>