Confirmed with milkv, only the sd card version is sold
by default for duo in the market. The spi pins are
provided through stamp holes, so that users can solder
the corresponding components on their baseboard during
secondary development.
In order to simplify maintenance work, the mainline
will only support the sd-card version and no longer
support spinor/spinand.
Updated config files the same in this patch.
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>