It's common for S-Mode proper U-Boot to retrieve a FDT blob along with
taking control from SBI firmware. Add a weak version of
board_fdt_blob_setup to make use of it by default, avoiding copy-pasting
similar functions among boards.
Signed-off-by: Yao Zi <ziyao@disroot.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
