rockchip: serial: restyle the serial_rockchip.c driver

rockchip: serial: restyle the serial_rockchip.c driver

The ns16550.c driver has the following conditions for .of_match:

CONFIG_IS_ENABLED(OF_REAL)

For Rockchip SoCs with TPL/SPL and platform data that need serial
support the serial_rockchip.c driver was made. It copies this data
and then calls ns16550_serial_probe(). With the addition of yet an other
SoC type this driver is in need for a little restyle.
Simplify struct rockchip_uart_plat and add extra SoCs with
DM_DRIVER_ALIAS(). Return -ENODEV when the ns16550.c driver
probe function is available.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>