s390/pci: improve unreg_ioat error handling

int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,

		       u64 base, u64 limit, u64 iota)

{

	struct mod_pci_args args = { base, limit, iota, 0 };

	u64 req = ZPCI_CREATE_REQ(zdev->fh, dmaas, ZPCI_MOD_FC_REG_IOAT);

	struct zpci_fib fib = {0};

	u8 status;

	WARN_ON_ONCE(iota & 0x3fff);

	args.iota |= ZPCI_IOTA_RTTO_FLAG;

	return mod_pci(zdev, ZPCI_MOD_FC_REG_IOAT, dmaas, &args);

	fib.pba = base;

	fib.pal = limit;

	fib.iota = iota | ZPCI_IOTA_RTTO_FLAG;

	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;

}

/* Modify PCI: Unregister I/O address translation parameters */

int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas)

{

	struct mod_pci_args args = { 0, 0, 0, 0 };

	u64 req = ZPCI_CREATE_REQ(zdev->fh, dmaas, ZPCI_MOD_FC_DEREG_IOAT);

	struct zpci_fib fib = {0};

	u8 cc, status;

	return mod_pci(zdev, ZPCI_MOD_FC_DEREG_IOAT, dmaas, &args);

	cc = zpci_mod_fc(req, &fib, &status);

	if (cc == 3) /* Function already gone. */

		cc = 0;

	return cc ? -EIO : 0;

}

/* Modify PCI: Set PCI function measurement parameters */

	 */

	WARN_ON(zdev->s390_domain);

	zpci_unregister_ioat(zdev, 0);

	if (zpci_unregister_ioat(zdev, 0))

		return;

	dma_cleanup_tables(zdev->dma_table);

	zdev->dma_table = NULL;

	vfree(zdev->iommu_bitmap);