[S390] qdio: tasklet termination in case of module unload

If the qdio module is unloaded the tiqdio tasklet must be terminated
by tasklet_kill. Move the tasklet_kill after the unregistration of
the adapter interrupt so the tiqdio tasklet will not be scheduled
anymore before calling tasklet_kill.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>