s390/qdio: make SBAL address array type-safe

There is no need to use void pointers, all drivers are in agreement
about the underlying data structure of the SBAL arrays.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>