board: roc-pc-rk3399: Add support for onboard LED's and push button to indicate power mode

Added support for onboard LED's and push button. When powered board will be
in low power mode(yellow LED), on button press, board enters full power mode
(red LED) and boots u-boot.

Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/tpl.c b/arch/arm/mach-rockchip/tpl.c
index 31a3eb4..a2b8d31 100644
--- a/arch/arm/mach-rockchip/tpl.c
+++ b/arch/arm/mach-rockchip/tpl.c
@@ -40,11 +40,18 @@
 	       TIMER_CONTROL_REG);
 }
 
+__weak int board_early_init_f(void)
+{
+	return 0;
+}
+
 void board_init_f(ulong dummy)
 {
 	struct udevice *dev;
 	int ret;
 
+	board_early_init_f();
+
 #if defined(CONFIG_DEBUG_UART) && defined(CONFIG_TPL_SERIAL_SUPPORT)
 	/*
 	 * Debug UART can be used from here if required: