OvmfPkg: QemuBootOrder: keep some boot options that have not been selected

OvmfPkg: QemuBootOrder: keep some boot options that have not been selected

Some of the active boot options that have not been selected over fw_cfg
should be preserved at the end of the boot order. For now we're adding
back everything that starts with neither PciRoot() nor HD(). This includes
the UEFI shell, memory-mapped from the firmware image.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Michael Chang <mchang@suse.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14668 6f19259b-4bc3-4df7-8a09-765794883524