efi_loader: consider no-map property of reserved memory

The device tree may contain a /reserved-memory node. The no-map property
of the sub-nodes signals if the memory may be accessed by the UEFI payload
or not.

In the EBBR specification (https://github.com/arm-software/ebbr

) the
modeling of the reserved memory has been clarified.

If a reserved memory node in the device tree has the no-map property map,
create a EfiReservedMemoryType memory map entry else use
EfiBootServicesData.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>