x86: Switch all boards to use DM SCSI

After MMC is converted to DM, convert to use DM SCSI as well for all
x86 boards and imply BLK for both MMC and SCSI drivers.

CONFIG_SCSI_DEV_LIST is no longer used. Clean them up.

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