extcon: Fix return value in extcon-class.c

Return the value obtained from the function extcon_register_interest
instead of -ENODEV.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>

drivers/extcon/extcon-class.c

@@ -472,7 +472,7 @@ int extcon_register_interest(struct extcon_specific_cable_nb *obj,
 
 		obj->cable_index = extcon_find_cable_index(obj->edev, cable_name);
 		if (obj->cable_index < 0)
-			return -ENODEV;
+			return obj->cable_index;
 
 		obj->user_nb = nb;