How to configure u-boot for 512 Mb Ram

I'm using an imx6slevk board with yocto bsp I use mfg tool to flash the images and it works fine for 1GB DRAM. Now I'm trying to change DRAM to 512 Mb I modified the dts file memory node:

memory {
    reg = <0x80000000 0x20000000>; //it was 0x40000000 
       };

I ran calibration tool and updated 2 registers

DATA 4 0x021b0848 0x4644484a //changed for 512 mb old value = 0x4241444a DATA 4 0x021b0850 0x3a363a30 //changed for 512 mb old value = 0x3030312b

However uboot log still shows 1GiB DRAM in flash log

U-Boot 2017.03-imx_v2017.03_4.9.88_2.0.0_ga+gb76bb1b (Sep 24 2019 - 11:04:03 +0530)

CPU: Freescale i.MX6SL rev1.2 996 MHz (running at 792 MHz)

CPU: Commercial temperature grade (0C to 95C) at 48C

Reset cause: POR

Model: Freescale i.MX6 SoloLite EVK Board

Board: MX6SLEVK

DRAM: 1 GiB

How can I change Dram from 1Gib o 512 Mib? The kernel doesn't flash without this.