fdt: introduce fdtdec_get_child_count

Introduce fdtdec_get_child_count for get the number of subnodes
of one parent node.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
2 files changed