of: Make of_find_node_by_path() handle /aliases

Make of_find_node_by_path() handle aliases as prefixes. To make this
work the name search is refactored to search by path component instead
of by full string. This should be a more efficient search, and it makes
it possible to start a search at a subnode of a tree.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[grant.likely: Rework to not require allocating at runtime]
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>