PNPACPI: pnpacpi_encode_ext_irq() wrongly set "irq" instead of "extended_irq"

pnpacpi_encode_ext_irq() should set resource->data.extended_irq, not
resource->data.irq.

This has been wrong since at least 2.6.12.  I haven't seen any bug
reports, but it's clearly incorrect.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>