INTEL-IGB: Convert iounmap to pci_iounmap

Use pci_iounmap instead of iounmap when the virtual mapping was done
with pci_iomap. A simplified version of the semantic patch that finds this
issue is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r@
expression addr;
@@
addr = pci_iomap(...)

@rr@
expression r.addr;
@@
* iounmap(addr)
// </smpl>

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>