s390/ap: resend enable adapter interrupt request.

The adapter interrupt for an APQN must be re-enabled after a reset.
This patch sends the interrupt enablement request again, if the APQN
is busy or the reset is still in progress.

Signed-off-by: Holger Dengler <hd@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>