Add some of DXE Services

This adds decls for some parts of DXE Services:

  gEfiDxeServicesTableGuid
  EFI_DXE_SERVICES_TABLE_GUID
  EFI_DXE_SERVICES_TABLE
  EFI_GCD_MEMORY_SPACE_DESCRIPTOR
  EFI_GCD_MEMORY_TYPE_T
  DST->GetMemorySpaceDescriptor
  DST->SetMemorySpaceAttributes

Signed-off-by: Peter Jones <pjones@redhat.com>

Add gEfiLoadedImageDevicePathProtocolGuid

Signed-off-by: Peter Jones <pjones@redhat.com>