rockchip: correct the bank0 ram size

The bank0 ram size should be the DRAM size minus reserved size,
the DRAM size may be 1GB, 2GB, 4GB, we can not hard code it.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Added DECLARE_GLOBAL_DATA_PTR for RK3328, RK3368 and RK3399:
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/arm/mach-rockchip/rk3328/rk3328.c b/arch/arm/mach-rockchip/rk3328/rk3328.c
index cec6f90..6764494 100644
--- a/arch/arm/mach-rockchip/rk3328/rk3328.c
+++ b/arch/arm/mach-rockchip/rk3328/rk3328.c
@@ -9,6 +9,8 @@
 #include <asm/armv8/mmu.h>
 #include <asm/io.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 static struct mm_region rk3328_mem_map[] = {
 	{
 		.virt = 0x0UL,
@@ -31,6 +33,17 @@
 
 struct mm_region *mem_map = rk3328_mem_map;
 
+int dram_init_banksize(void)
+{
+	size_t max_size = min((unsigned long)gd->ram_size, gd->ram_top);
+
+	/* Reserve 0x200000 for ATF bl31 */
+	gd->bd->bi_dram[0].start = 0x200000;
+	gd->bd->bi_dram[0].size = max_size - gd->bd->bi_dram[0].start;
+
+	return 0;
+}
+
 int arch_cpu_init(void)
 {
 	/* We do some SoC one time setting here. */