[MIPS] Eleminate interrupt migration helper use.

> #define hw_interrupt_type       irq_chip
> typedef struct irq_chip         hw_irq_controller;
> #define no_irq_type             no_irq_chip
> typedef struct irq_desc         irq_desc_t;

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/sgi-ip27/ip27-timer.c b/arch/mips/sgi-ip27/ip27-timer.c
index 3ca614a..f3775aa 100644
--- a/arch/mips/sgi-ip27/ip27-timer.c
+++ b/arch/mips/sgi-ip27/ip27-timer.c
@@ -205,7 +205,7 @@
 {
 }
 
-static struct hw_interrupt_type rt_irq_type = {
+static struct irq_chip rt_irq_type = {
 	.typename	= "SN HUB RT timer",
 	.startup	= startup_rt_irq,
 	.shutdown	= shutdown_rt_irq,