dm: core: implement phandle ofnode_options helper

Implement ofnode_options phandle helper to get an ofnode from a phandle
option in /options/u-boot.

This helper can be useful since new DT yaml usually require to link a
phandle of a node instead of referencing it by name or other indirect
way.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2 files changed