Some existing PCI adapters with UEFI option ROMs make unaligned requests through...

Some existing PCI adapters with UEFI option ROMs make unaligned requests through the PCI I/O Protocol. Add support for unaligned requests in the PCI IO protocol implementation in the PCI Bus driver to be compatible with those UEFI option ROMs.

This solution defines a PCD Feature Flag to enabled support for unaligned requests through the PCI I/O Protocol.  This flag is disabled by default. Platforms that do want to support such EFI/UEFI drivers that make unaligned PCI I/O requests should enable this feature.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11016 6f19259b-4bc3-4df7-8a09-765794883524