[S390] zcrypt: Fix ap_poll_requests counter in lost requests error path.

In the unlikely event that an AP device lost requests, don't forget to
update the ap_poll_requests counter too. Same must happen in case an AP
device is removed while there are still outstanding requests.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ralph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>