Input: twl4030-vibra - fix sibling-node lookup

A helper purported to look up a child node based on its name was using
the wrong of-helper and ended up prematurely freeing the parent of-node
while searching the whole device tree depth-first starting at the parent
node.

Fixes: 64b9e4d8 ("input: twl4030-vibra: Support for DT booted kernel")
Fixes: e661d0a0 ("Input: twl4030-vibra - fix ERROR: Bad of_node_put() warning")
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>