drivers: tty: goldfish: Add device tree bindings

Enable support for registering this device using the device tree.
Device tree node example for registering Goldfish TTY device :

goldfish_tty@1f004000 {
    interrupts = <0xc>;
    reg = <0x1f004000 0x1000>;
    compatible = "google,goldfish-tty";
};

Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Jin Qian <jinqian@android.com>
Signed-off-by: Alan <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>