MIPS: lantiq: Remove unnecessary include of <linux/of_irq.h>

arch/mips/pci/fixup-lantiq.c requires nothing from <linux/of_irq.h>, so
remove the include of it.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/pci/fixup-lantiq.c

@@ -4,7 +4,6 @@
  *  Copyright (C) 2012 John Crispin <john@phrozen.org>
  */
 
-#include <linux/of_irq.h>
 #include <linux/of_pci.h>
 #include <linux/pci.h>