Input: twl6040-vibra - fix child-node lookup

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.

Later sanity checks on node properties (which would likely be missing)
should prevent this from causing much trouble however, especially as the
original premature free of the parent node has already been fixed
separately (but that "fix" was apparently never backported to stable).

Fixes: e7ec014a ("Input: twl6040-vibra - update for device tree support")
Fixes: c52c545e ("Input: twl6040-vibra - fix DT node memory management")
Cc: stable <stable@vger.kernel.org>     # 3.6
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com> (on Pyra OMAP5 hardware)
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>