[IA64] eliminate compile time warnings

This patch removes following compile time warnings:

drivers/pci/pci-sysfs.c: In function `pci_read_legacy_io':
drivers/pci/pci-sysfs.c:257: warning: implicit declaration of function `ia64_pci_legacy_read'
drivers/pci/pci-sysfs.c: In function `pci_write_legacy_io':
drivers/pci/pci-sysfs.c:280: warning: implicit declaration of function `ia64_pci_legacy_write'

It also fixes wrong definition of ia64_pci_legacy_write (type of `bus' is not
`pci_dev', but `pci_bus').

Signed-Off-By: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>