Mark the memory region with NOMAP flag instead of completely removing it
from the memory blocks. That makes the FDT handling consistent with the EFI
memory map handling.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20210115114544.1830068-2-qperret@google.comSigned-off-by: Rob Herring <robh@kernel.org>