arm64: dts: rockchip: Update the PinePhone Pro panel description

arm64: dts: rockchip: Update the PinePhone Pro panel description

Fix a few issues in the panel section of the PinePhone Pro DTS:
  - add the second part of the Himax HX8394 LCD panel controller
    compatible
  - as proposed by Diederik de Haas, reuse the mipi_out and ports
    definitions from rk3399-base.dtsi instead of redefining them
  - add a pinctrl for the LCD_RST signal for LCD1, derived from
    LCD1_RST, which is on GPIO4_D1, as documented on pages 11
    and 16 of the PinePhone Pro schematic

Signed-off-by: Olivier Benjamin <olivier.benjamin@bootlin.com>
Reviewed-by: Diederik de Haas <didi.debian@cknow.org>
Link: https://lore.kernel.org/r/20250619-dtb_fixes-v3-1-9cb02ddd8ce4@bootlin.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>