irqchip/i8259: Set I/O port resource types correctly

Set I/O port resource structs to have IORESOURCE_IO in their type field.

Previously we marked these as merely IORESOURCE_BUSY without indicating the
type.  Setting the type doesn't fix any functional problem but makes %pR
on the resource work better.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>