extcon: Implement OF-based extcon lookup properly

Platform bus is not the only way to have extcon devices, so current
implementation of of_extcon_get_extcon_dev() is broken. Also using
parent device node only to get device name is quite ugly.

This patch reimplements of_extcon_get_extcon_dev() to do exactly the
same as extcon_get_extcon_dev() but instead of comparing names, compare
node pointers.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
[mszyprow: simplified the code]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/extcon/extcon-class.c

@@ -29,6 +29,7 @@
 #include <linux/fs.h>
 #include <linux/err.h>
 #include <linux/extcon.h>
+#include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/of.h>
@@ -997,13 +998,16 @@ struct extcon_dev *extcon_get_edev_by_phandle(struct device *dev, int index)
 		return ERR_PTR(-ENODEV);
 	}
 
-	edev = extcon_get_extcon_dev(node->name);
-	if (!edev) {
-		dev_err(dev, "unable to get extcon device : %s\n", node->name);
-		return ERR_PTR(-ENODEV);
+	mutex_lock(&extcon_dev_list_lock);
+	list_for_each_entry(edev, &extcon_dev_list, entry) {
+		if (edev->dev.parent && edev->dev.parent->of_node == node) {
+			mutex_unlock(&extcon_dev_list_lock);
+			return edev;
+		}
 	}
+	mutex_unlock(&extcon_dev_list_lock);
 
-	return edev;
+	return ERR_PTR(-EPROBE_DEFER);
 }
 #else
 struct extcon_dev *extcon_get_edev_by_phandle(struct device *dev, int index)