s390: use the correct count for __iowrite64_copy()

The signature for __iowrite64_copy() requires the number of 64 bit
quantities, not bytes. Multiple by 8 to get to a byte length before
invoking zpci_memcpy_toio()

Fixes: 87bc359 ("s390/pci: speed up __iowrite64_copy by using pci store block insn")
Acked-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/0-v1-9223d11a7662+1d7785-s390_iowrite64_jgg@nvidia.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/pci/pci.c

@@ -252,7 +252,7 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 /* combine single writes by using store-block insn */
 void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
 {
-       zpci_memcpy_toio(to, from, count);
+	zpci_memcpy_toio(to, from, count * 8);
 }
 
 void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,