OvmfPkg: QemuBootOrderLib: OFW-to-UEFI translation for virtio-mmio

OvmfPkg: QemuBootOrderLib: OFW-to-UEFI translation for virtio-mmio

The TranslateMmioOfwNodes() function recognizes the following OpenFirmware
device paths:

  virtio-blk:       /virtio-mmio@000000000a003c00/disk@0,0
  virtio-scsi disk: /virtio-mmio@000000000a003a00/channel@0/disk@2,3
  virtio-net NIC:   /virtio-mmio@000000000a003e00/ethernet-phy@0

The new translation can be enabled with the
"PcdQemuBootOrderMmioTranslation" Feature PCD. This PCD also controls if
the "survival policy" covers unselected boot options that start with the
virtio-mmio VenHw() node.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16575 6f19259b-4bc3-4df7-8a09-765794883524