alpha: irq clean up

Stop touching irq_desc[irq] directly, instead use accessor
functions provided. Use irq_has_action instead of directly
testing the irq_desc.

Tested-by: Michael Cree <mcree@orcon.net.nz>
Signed-off-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
diff --git a/arch/alpha/kernel/sys_cabriolet.c b/arch/alpha/kernel/sys_cabriolet.c
index ba38fcd..01a932b 100644
--- a/arch/alpha/kernel/sys_cabriolet.c
+++ b/arch/alpha/kernel/sys_cabriolet.c
@@ -67,7 +67,7 @@
 static void
 cabriolet_end_irq(unsigned int irq)
 { 
-	if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
+	if (!(irq_to_desc(irq)->status & (IRQ_DISABLED|IRQ_INPROGRESS)))
 		cabriolet_enable_irq(irq);
 }
 
@@ -124,7 +124,7 @@
 		for (i = 16; i < 35; ++i) {
 			set_irq_chip_and_handler(i, &cabriolet_irq_type,
 				alpha_do_IRQ);
-			irq_desc[i].status |= IRQ_LEVEL;
+			irq_to_desc(i)->status |= IRQ_LEVEL;
 		}
 	}