rockchip: rk3399: Include uart related pinctrl nodes in TPL/SPL

rockchip: rk3399: Include uart related pinctrl nodes in TPL/SPL

The initial serial console UART iomux is typically configured in
board_debug_uart_init() at TPL stage on Rockchip platform.

Later stages typically use pinctrl driver to configure iomux UART once
again based on the control FDT.

Include uart related pinctrl nodes in TPL/SPL control FDT to make it
possible for pinctrl driver to configure UART iomux at TPL/SPL stage.

Following debug log message may also be seen at U-Boot pre-reloc stage:

  ns16550_serial serial@ff1a0000: pinctrl_select_state_full: uclass_get_device_by_phandle_id: err=-19

This can be resolved by including bootph prop for U-Bood pre-reloc
phase (bootph-some-ram or bootph-all). However, this has intentionally
been excluded due to including it unnecessarily slows down boot around
200-400 ms.

Also add the clock-frequency prop similar to what has been done for
other Rockchip SoCs.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>