s390/qdio: correct program-controlled interruption checking

Get rid of compile warning in qdio_int_handler_pci() when checking
for program-controlled interruption on outbound queues.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>