tty: serial: ip22zilog: Use platform device for probing

In the Linux kernel, the following vulnerability has been resolved: tty: serial: ip22zilog: Use platform device for probing After commit 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") serial drivers need to provide a device in struct uart_port.dev otherwise an oops happens. To fix this issue for ip22zilog driver switch driver to a platform driver and setup the serial device in sgi-ip22 code.