OvmfPkg: QemuBootOrderLib: recognize NVMe devices

OvmfPkg: QemuBootOrderLib: recognize NVMe devices

This patch enables QemuBootOrderLib to parse OFW device paths formatted by
QEMU commit a907ec52cc1a:

  nvme: generate OpenFirmware device path in the "bootorder" fw_cfg file

With both patches applied, OVMF will honor the bootindex=N property of the
NVMe device:

  -drive id=drive0,if=none,format=FORMAT,file=PATHNAME \
  -device nvme,drive=drive0,serial=SERIAL,bootindex=N
                                          ^^^^^^^^^^^

Cc: Vladislav Vovchenko <vladislav.vovchenko@sk.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Reference: https://github.com/tianocore/edk2/issues/48
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Tested-by: Vladislav Vovchenko <vladislav.vovchenko@sk.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19792 6f19259b-4bc3-4df7-8a09-765794883524