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/irq_pyxis.c b/arch/alpha/kernel/irq_pyxis.c
index 4e1904c..9f603cf 100644
--- a/arch/alpha/kernel/irq_pyxis.c
+++ b/arch/alpha/kernel/irq_pyxis.c
@@ -50,7 +50,8 @@
 static void
 pyxis_end_irq(unsigned int irq)
 {
-	if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
+	struct irq_desc *desc = irq_to_desc(irq);
+	if (desc || !(desc->status & (IRQ_DISABLED|IRQ_INPROGRESS)))
 		pyxis_enable_irq(irq);
 }
 
@@ -120,7 +121,7 @@
 		if ((ignore_mask >> i) & 1)
 			continue;
 		set_irq_chip_and_handler(i, &pyxis_irq_type, alpha_do_IRQ);
-		irq_desc[i].status |= IRQ_LEVEL;
+		irq_to_desc(i)->status |= IRQ_LEVEL;
 	}
 
 	setup_irq(16+7, &isa_cascade_irqaction);