dm: core: Move "/clock" node scan into function

dm: core: Move "/clock" node scan into function

Create separate function for scanning node by path and
move "/clock" node scan code into that function.

This will be usable if scanning of more node is required.

Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>