The routine PageAttributeToGcdAttribute() is exported by ArmMmuLib
but only ever used in the implementation of CpuDxe. So let's move
the function there and make it STATIC.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>