s390/pci: improve ZPCI_* macros

Most of the constants defined in pci_io.h depend on each other
and thus can be calculated.

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>