s390/qdio: remove Input tasklet code

Both qeth and zfcp have fully moved to the polling-driven flow for
Input Queues with commit 0a6e6345 ("s390/qdio: extend polling
support to multiple queues") and commit 0b524abc

 ("scsi: zfcp: Lift
Input Queue tasklet from qdio").

So remove the tasklet code for Input Queues, streamline the IRQ handlers
and push the tasklet struct into struct qdio_output_q.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>