dm: x86: minnowmax: Move PCI to use driver model

Adjust minnowmax to use driver model for PCI. This requires adding a device
tree node to specify the ranges, removing the board-specific PCI code and
ensuring that the host bridge is configured.

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