sunxi: d1: board: sunxi: fdt fixup of dram size for d1 platforms

[geomatsi]

Hi @smaeul

While adding support for this board in Buildroot, I discovered that I couldn't simply switch to using the mainline Linux DTS. This merge request includes two patches that enable its use without further modifications. In brief:

• the first commit patches dtb for Linux with DRAM information obtained by SPL
• the second commit tunes load addresses in U-Boot default environment in order to add support for larger Linux images

Please let me know if I got it wrong and there is a proper default way to handle this.

Regards, Sergey