x86: quark: Turn on legacy segments decode

By default the legacy segments (A0000h-B0000h, E0000h-F0000h)
do not decode to system RAM. Turn on the decode so that we can
write configuration tables in the F segment.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>