backlight: tps65217_bl: Fix Device Tree node lookup

BugLink: https://bugs.launchpad.net/bugs/1784382

commit 2b12dfa1 upstream.

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.

This would only cause trouble if the child node is missing while there
is an unrelated node named "backlight" elsewhere in the tree.

Cc: stable <stable@vger.kernel.org>     # 3.7
Fixes: eebfdc17 ("backlight: Add TPS65217 WLED driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/video/backlight/tps65217_bl.c

@@ -184,11 +184,11 @@ static struct tps65217_bl_pdata *
 tps65217_bl_parse_dt(struct platform_device *pdev)
 {
 	struct tps65217 *tps = dev_get_drvdata(pdev->dev.parent);
-	struct device_node *node = of_node_get(tps->dev->of_node);
+	struct device_node *node;
 	struct tps65217_bl_pdata *pdata, *err;
 	u32 val;
 
-	node = of_find_node_by_name(node, "backlight");
+	node = of_get_child_by_name(tps->dev->of_node, "backlight");
 	if (!node)
 		return ERR_PTR(-ENODEV);