HID: fix reversed logic in disconnect testing of hiddev

The logic for testing for disconnection is reversed in an ioctl leading
to false reports of disconnection.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Tested-by: Folkert van Heusden <folkert@vanheusden.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
index d73eea3..4940e4d 100644
--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -656,7 +656,7 @@
 
 	case HIDIOCGSTRING:
 		mutex_lock(&hiddev->existancelock);
-		if (!hiddev->exist)
+		if (hiddev->exist)
 			r = hiddev_ioctl_string(hiddev, cmd, user_arg);
 		else
 			r = -ENODEV;