s390/ap: fix error handling in __verify_queue_reservations()

The AP bus's __verify_queue_reservations function increments the ref count
for the device driver passed in as a parameter, but fails to decrement it
before returning control to the caller. This will prevents any subsequent
removal of the module.

Signed-off-by: Tony Krowiak <[email protected]>
Reported-by: Tony Krowiak <[email protected]>
Reviewed-by: Harald Freudenberger <[email protected]>
Fixes: 4f8206b ("s390/ap: driver callback to indicate resource in use")
Link: https://lore.kernel.org/r/[email protected]
Cc: [email protected]
[[email protected] fixed description, added Fixes and Link]
Signed-off-by: Alexander Gordeev <[email protected]>

Author: Tony Krowiak

drivers/s390/crypto/ap_bus.c

@@ -1435,7 +1435,7 @@ static int __verify_queue_reservations(struct device_driver *drv, void *data)
 	if (ap_drv->in_use) {
 		rc = ap_drv->in_use(ap_perms.apm, newaqm);
 		if (rc)
-			return -EBUSY;
+			rc = -EBUSY;
 	}
 
 	/* release the driver's module */