[IA64] incorrect return from ia64_pci_legacy_write()

The function ia64_pci_legacy_write() returns 0 for everything
except errors.  This return value gets sent back to the user from
pci_write_legacy_io(), making it look like every write fails.  The trivial
patch below copies the behavior of the SGI sn machvec and does what
would be expected from something implementing a write() function.
Signed-off-by: NAlex Williamson <alex.williamson@hp.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

arch/ia64/pci/pci.c

@@ -700,7 +700,7 @@ int ia64_pci_legacy_read(struct pci_bus *bus, u16 port, u32 *val, u8 size)
  */
 int ia64_pci_legacy_write(struct pci_dev *bus, u16 port, u32 val, u8 size)
 {
-	int ret = 0;
+	int ret = size;
 
 	switch (size) {
 	case 1: