Among the patches adding support for MT7988 also came the switch to
use fdtdec_setup_mem_size_base() and no longer rely on CFG_SYS_SDRAM_BASE.
Take care of our downstream boards which did not have a 'memory' node in
their device trees.
Fixes: 572ea68070 ("uboot-mediatek: add patches for MT7988 and builds for RFB")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
0415aba6a9