rockchip: rk3188: use board_debug_uart_init() for UART io init

Sync with other rockchip SoCs, use board_debug_uart_init() to
init default UART iomux.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/arm/mach-rockchip/rk3188-board-spl.c b/arch/arm/mach-rockchip/rk3188-board-spl.c
index 1877855..3c6c3d3 100644
--- a/arch/arm/mach-rockchip/rk3188-board-spl.c
+++ b/arch/arm/mach-rockchip/rk3188-board-spl.c
@@ -93,24 +93,21 @@
 	return ret;
 }
 
-#define GRF_BASE	0x20008000
-
-void board_init_f(ulong dummy)
+void board_debug_uart_init(void)
 {
-	__maybe_unused struct rk3188_grf * const grf = (void *)GRF_BASE;
-	struct udevice *pinctrl, *dev;
-	int ret;
-
-	/* Example code showing how to enable the debug UART on RK3188 */
-#ifdef EARLY_UART
+	/* Enable early UART on the RK3188 */
+#define GRF_BASE	0x20008000
+	struct rk3188_grf * const grf = (void *)GRF_BASE;
 	enum {
 		GPIO1B1_SHIFT		= 2,
 		GPIO1B1_MASK		= 3,
-		GPIO1B1_UART2_SOUT	= 1,
+		GPIO1B1_GPIO		= 0,
+		GPIO1B1_UART2_SOUT,
 
 		GPIO1B0_SHIFT		= 0,
 		GPIO1B0_MASK		= 3,
-		GPIO1B0_UART2_SIN	= 1,
+		GPIO1B0_GPIO		= 0,
+		GPIO1B0_UART2_SIN,
 	};
 
 	/* Enable early UART on the RK3188 */
@@ -119,6 +116,15 @@
 		     GPIO1B0_MASK << GPIO1B0_SHIFT,
 		     GPIO1B1_UART2_SOUT << GPIO1B1_SHIFT |
 		     GPIO1B0_UART2_SIN << GPIO1B0_SHIFT);
+}
+
+void board_init_f(ulong dummy)
+{
+	struct udevice *pinctrl, *dev;
+	int ret;
+
+#define EARLY_UART
+#ifdef EARLY_UART
 	/*
 	 * Debug UART can be used from here if required:
 	 *