Some dts files for the Kernel specify a reserved memory area using the
/memreserve/ dtc directive. These entries get lost during
unflattening/flattening the device tree and are never passed to the
Kernel.

This patch fixes this behaviour. This is done by copying the entries
into a /memreserve node in the unflattened tree and moving them back
during flattening the tree. The entries added by barebox dynamically
are appended to the static entries from the original dtb.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>