x86/PCI: select direct access mode for mmconfig option

Direct access is needed in mmconf mode too. There are two reasons:
1. we need it to access first 256 bytes. We have bug before that
   using mmconf to access pci config space hangs system (when
   resizing BARs), so we use type1 config for legacy config space.
2. when doing mmconfg bar checking, we need access ACPI _CRS,
   which might access PCI config space.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>