dm: add cells_count parameter in live DT APIs of_parse_phandle_with_args

dm: add cells_count parameter in live DT APIs of_parse_phandle_with_args

In the live tree API ofnode_parse_phandle_with_args, the cell_count
argument must be used when cells_name is NULL.

But this argument is not provided to the live DT function
of_parse_phandle_with_args even it is provided to
fdtdec_parse_phandle_with_args.

This patch adds support of the cells_count parameter in dev_ and
of_node API to allow migration and support of live DT:
- of_parse_phandle_with_args

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>