rockchip: rk3288: add board_debug_uart_init()

Use board_debug_uart_init() for UART iomux init instead of
do it in board_init_f, and move the function to soc file so
that we can find all the soc/board setting in soc file and
use a common board file for all rockchip SoCs later.

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/rk3288-board-spl.c b/arch/arm/mach-rockchip/rk3288-board-spl.c
index 937a99d..d8d215d 100644
--- a/arch/arm/mach-rockchip/rk3288-board-spl.c
+++ b/arch/arm/mach-rockchip/rk3288-board-spl.c
@@ -109,16 +109,7 @@
 	struct udevice *dev;
 	int ret;
 
-	/* Example code showing how to enable the debug UART on RK3288 */
-#include <asm/arch-rockchip/grf_rk3288.h>
-	/* Enable early UART on the RK3288 */
-#define GRF_BASE	0xff770000
-	struct rk3288_grf * const grf = (void *)GRF_BASE;
-
-	rk_clrsetreg(&grf->gpio7ch_iomux, GPIO7C7_MASK << GPIO7C7_SHIFT |
-		     GPIO7C6_MASK << GPIO7C6_SHIFT,
-		     GPIO7C7_UART2DBG_SOUT << GPIO7C7_SHIFT |
-		     GPIO7C6_UART2DBG_SIN << GPIO7C6_SHIFT);
+#ifdef CONFIG_DEBUG_UART
 	/*
 	 * Debug UART can be used from here if required:
 	 *
@@ -129,6 +120,7 @@
 	 */
 	debug_uart_init();
 	debug("\nspl:debug uart enabled in %s\n", __func__);
+#endif
 	ret = spl_early_init();
 	if (ret) {
 		debug("spl_early_init() failed: %d\n", ret);