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 <akrowiak@linux.ibm.com>
Reported-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Fixes: 4f8206b8

 ("s390/ap: driver callback to indicate resource in use")
Link: https://lore.kernel.org/r/20220706222619.602094-1-akrowiak@linux.ibm.com
Cc: stable@vger.kernel.org
[agordeev@linux.ibm.com fixed description, added Fixes and Link]
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>