powerpc: Remove get_irq_desc()

get_irq_desc() is a powerpc-specific version of irq_to_desc(). That
is reason enough to remove it, but it also doesn't know about sparse
irq_desc support which irq_to_desc() does (when we enable it).

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/sysdev/i8259.c b/arch/powerpc/sysdev/i8259.c
index a96584a..78ed945 100644
--- a/arch/powerpc/sysdev/i8259.c
+++ b/arch/powerpc/sysdev/i8259.c
@@ -175,12 +175,12 @@
 
 	/* We block the internal cascade */
 	if (hw == 2)
-		get_irq_desc(virq)->status |= IRQ_NOREQUEST;
+		irq_to_desc(virq)->status |= IRQ_NOREQUEST;
 
 	/* We use the level handler only for now, we might want to
 	 * be more cautious here but that works for now
 	 */
-	get_irq_desc(virq)->status |= IRQ_LEVEL;
+	irq_to_desc(virq)->status |= IRQ_LEVEL;
 	set_irq_chip_and_handler(virq, &i8259_pic, handle_level_irq);
 	return 0;
 }