rockchip: rk1808: set dram area unsecure in spl

So that the mmc controller can read data to dram since the mmc
controller is unsecure.

Change-Id: Iaf8f5cebeacbc034eb129c6b52a702abdbd7fed3
Signed-off-by: Jason Zhu <jason.zhu@rock-chips.com>

arch/arm/mach-rockchip/rk1808/rk1808.c

@@ -65,12 +65,19 @@ enum {
 	UART2_IO_SEL_USB,
 };
 
+#define SECURE_FIRE_WALL 0xff590040
+
 int arch_cpu_init(void)
 {
 	/* Set cif qos priority */
 	writel(QOS_PRIORITY_LEVEL(2, 2), NIU_CIF_ADDR);
 	writel(QOS_PRIORITY_LEVEL(2, 2), NIU_ISP_ADDR);
 
+	/* Set dram to unsecure */
+#ifdef CONFIG_SPL_BUILD
+	writel(0, SECURE_FIRE_WALL);
+#endif
+
 	return 0;
 }