drivers: of: add function to scan fdt nodes given by path

drivers: of: add function to scan fdt nodes given by path

Add a function to scan the flattened device-tree starting from the
node given by the path. It is used to extract information (like reserved
memory), which is required on early boot before we can unflatten the tree.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
(cherry picked from commit 57d74bcf3072b65bde5aa540cedc976a75c48e5c)
Signed-off-by: Mark Brown <broonie@linaro.org>