extcon: remove redundant assignment to variable idx

The variable idx is being initialized with a value that is never read
and it is being updated later with a new value. The initialization is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>

drivers/extcon/extcon.c

···
 			     struct notifier_block *nb)
 {
 	unsigned long flags;
-	int ret, idx = -EINVAL;
+	int ret, idx;
 
 	if (!edev || !nb)
 		return -EINVAL;