MdeModulePkg: implement generic PCI I/O driver for non-discoverable devices

MdeModulePkg: implement generic PCI I/O driver for non-discoverable devices

This implements support for non-discoverable PCI compatible devices, i.e,
devices that are not on a PCI bus but that can be controlled by generic PCI
drivers in EDK2.

This is implemented as a UEFI driver, which means we take full advantage
of the UEFI driver model, and only instantiate those devices that are
necessary for booting.

Care is taken to deal with DMA addressing limitations: DMA mappings and
allocations are moved below 4 GB if the PCI driver has not informed us
that the device being driven is 64-bit DMA capable. DMA is implemented as
coherent, support for non-coherent DMA is implemented by a subsequent patch.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
Tested-by: Marcin Wojtas <mw@semihalf.com>