doc: add include/dm/of*.h to the HTML documentation

Correct Sphinx style comments in include/dm/ofnode.h
and add the device tree node API to the HTML documentation;
the ofnode functions are compatible with Live tree or with flat
device tree.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
6 files changed