s390/qdio: clarify size of the QIB parm area

The QIB parm area is 128 bytes long. Current code consistently misuses
an _entirely unrelated_ QDIO constant, merely because it has the same
value. Stop doing so.

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