[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/kernel/irq-rm9000.c b/arch/mips/kernel/irq-rm9000.c
index 25109c1..62f011b 100644
--- a/arch/mips/kernel/irq-rm9000.c
+++ b/arch/mips/kernel/irq-rm9000.c
@@ -105,7 +105,7 @@
 		unmask_rm9k_irq(irq);
 }
 
-static hw_irq_controller rm9k_irq_controller = {
+static struct irq_chip rm9k_irq_controller = {
 	.typename = "RM9000",
 	.startup = rm9k_cpu_irq_startup,
 	.shutdown = rm9k_cpu_irq_shutdown,
@@ -115,7 +115,7 @@
 	.end = rm9k_cpu_irq_end,
 };
 
-static hw_irq_controller rm9k_perfcounter_irq = {
+static struct irq_chip rm9k_perfcounter_irq = {
 	.typename = "RM9000",
 	.startup = rm9k_perfcounter_irq_startup,
 	.shutdown = rm9k_perfcounter_irq_shutdown,