extcon: Add extcon_get_edev_name() API to get the extcon device name

This patch adds the extcon_get_edev_name() API to get the name of extcon device
because all information inclued in the structure extcon_dev should be accessed
by extcon core API instead of directly accessing the data.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
diff --git a/include/linux/extcon.h b/include/linux/extcon.h
index 36f49c4..e2cf625 100644
--- a/include/linux/extcon.h
+++ b/include/linux/extcon.h
@@ -259,6 +259,10 @@
  * This function use phandle of devicetree to get extcon device directly.
  */
 extern struct extcon_dev *extcon_get_edev_by_phandle(struct device *dev, int index);
+
+/* Following API to get information of extcon device */
+extern const char *extcon_get_edev_name(struct extcon_dev *edev);
+
 #else /* CONFIG_EXTCON */
 static inline int extcon_dev_register(struct extcon_dev *edev)
 {