rockchip: Add setup_gpio_pins for board-specific early setup

Some boards require touching GPIOs in some ways to setup some hardware
in a known state, which may not be the expected state during boot.

This follows the logic used by `led_setup`.

Either expected by U-Boot or the booted Operating System.

Signed-off-by: Samuel Dionne-Riel <samuel@dionne-riel.com>

(Originally part of commit 3e03219)
Co-authored-by: Antoni Przybylik <antoni.przybylik@wp.pl>

Originally added for the Pinephone Pro. Now needed for the Pinebook Pro
too.

Changes from Samuel Dionne-Riel <samuel@dionne-riel> adding setup_gpio_pins
as a weak function, fixing unified tree build.

(cherry picked from commit ac9c738)

Author: antoniprzybylik

arch/arm/mach-rockchip/rk3399/rk3399.c

@@ -254,9 +254,14 @@ void __weak led_setup(void)
 {
 }
 
+void __weak setup_gpio_pins(void)
+{
+}
+
 void spl_board_init(void)
 {
 	led_setup();
+	setup_gpio_pins();
 
 	if (IS_ENABLED(CONFIG_SPL_GPIO)) {
 		struct rockchip_cru *cru = rockchip_get_cru();