s390/pci: Fix reset of IOMMU software counters

s390/pci: Fix reset of IOMMU software counters

Together with enabling the Function Measurement Block
zpci_fmb_enable_device() also resets the software counters. This allows
to use "echo 0 > /sys/kernel/debug/pci/<dev>/statistics" followed by
echo "1 > /../statistics" to reset all counters. In commit c76c067e488c
("s390/pci: Use dma-iommu layer") this use of the now obsolete counters
in struct zpci_device was missed as was their removal. Fix this by
resetting the new counters and removing the old ones.

Fixes: c76c067e488c ("s390/pci: Use dma-iommu layer")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20231004-dma_iommu_fix-v1-1-129777cd8232@linux.ibm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>