video: fbdev: atmel_lcdfb: fix display-timings lookup

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

To make things worse, the parent display node was also prematurely
freed.

Note that the display and timings node references are never put after a
successful dt-initialisation so the nodes would leak on later probe
deferrals and on driver unbind.

Fixes: b985172b ("video: atmel_lcdfb: add device tree suport")
Cc: stable <stable@vger.kernel.org>     # 3.13
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>