s390/qdio: fill SL with absolute addresses

As the comment says, sl->sbal holds an absolute address. qeth currently
solves this through wild casting, while zfcp doesn't care.

Handle this properly in the code that actually builds the SL.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Steffen Maier <maier@linux.ibm.com> [for qdio]
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>