ACPI : Not register gsi for PCI IDE controller in legacy mode

When PCI IDE controller works in legacy mode and no PRT entry is found
in ACPI PRT table, OSPM will neither read the irq number from the IDE
PCI configuration space nor call the function of acpi_register_gsi to
register gsi.

http://bugzilla.kernel.org/show_bug.cgi?id=5637

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>