Fix child node-lookup during probe, which ended up searching the whole
device tree depth-first starting at parent rather than just matching on
its children.

To make things worse, the parent node was prematurely freed, while the
child node was leaked.

Fixes: 2e57d567 ("mfd: 88pm860x: Device tree support")
Cc: stable <stable@vger.kernel.org>     # 3.7
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>