For LD20 SoC, the last 64 byte of each DRAM bank is used for the dynamic training of DRAM PHY. The regions must be reserved in DT to prevent the kernel from using them. Now gd->bd->bi_dram reflects the actual memory banks. Just use it instead of getting access to the board parameters. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>