rockchip: rk3399: Clean up and seprate secure parts from SoC codes

The goal is that make clear the secure and SoC codes. Now cleaning them
will help secure code extensions for RK3399 in the future.

Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
diff --git a/plat/rockchip/rk3399/drivers/dram/dram.c b/plat/rockchip/rk3399/drivers/dram/dram.c
index 5f6f0fc..1dfb3e5 100644
--- a/plat/rockchip/rk3399/drivers/dram/dram.c
+++ b/plat/rockchip/rk3399/drivers/dram/dram.c
@@ -30,6 +30,7 @@
 
 #include <dram.h>
 #include <plat_private.h>
+#include <secure.h>
 #include <soc.h>
 #include <rk3399_def.h>