s390/pci: provide ZPCI_ADDR macro

Provide and use a ZPCI_ADDR macro as the complement of ZPCI_IDX
to get rid of some constants in the code.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>