of: Add of_get_next_status_child() and makes more generic of_get_next

Linux Kernel has of_get_next_available_child().
Add more generic of_get_next_status_child() to enable to use same
logic for other status.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87bk9ugfb0.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>