s390/qdio: de-duplicate tiqdio_inbound_processing()

Except for some initial thinint-only steps, the processing is identical
to the non-thinint case. So re-use the existing helper.

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>