rockchip: rk3368: add sdram driver for U-Boot

Add sdram driver in U-Boot for get the correct sdram size from
sys_reg, so that U-Boot can co-work with Rockchip loader or SPL
to get different dram capability and then tell the kernel.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/arch/arm/include/asm/arch-rockchip/grf_rk3368.h b/arch/arm/include/asm/arch-rockchip/grf_rk3368.h
index 3233dc3..93c4e7d 100644
--- a/arch/arm/include/asm/arch-rockchip/grf_rk3368.h
+++ b/arch/arm/include/asm/arch-rockchip/grf_rk3368.h
@@ -92,8 +92,10 @@
 	u32 gpio0d_drv;
 	u32 gpio0l_sr;
 	u32 gpio0h_sr;
+	u32 reserved[(0x200 - 0x34) / 4 - 1];
+	u32 os_reg[4];
 };
-check_member(rk3368_pmu_grf, gpio0h_sr, 0x34);
+check_member(rk3368_pmu_grf, os_reg[3], 0x20c);
 
 /*GRF_GPIO0C_IOMUX*/
 enum {