s390/tape: fix virtual vs physical address confusion

Fix virtual vs physical address confusion and use new dma types and helper
functions to allow for type checking. This does not fix a bug since virtual
and physical address spaces are currently the same.

Tested-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>