forked from OERV-BSP/u-boot
TH1520 SoC ships DMA peripherals that could only reach the first 32-bit range of memory, for example, the GMAC controllers. Let's limit the usable top of RAM below 4GiB to ensure DMA allocations are accessible to all peripherals. Signed-off-by: Yao Zi <ziyao@disroot.org> Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>