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/cpm1.c b/arch/powerpc/sysdev/cpm1.c
index 82424cd..5235373 100644
--- a/arch/powerpc/sysdev/cpm1.c
+++ b/arch/powerpc/sysdev/cpm1.c
@@ -102,7 +102,7 @@
 {
 	pr_debug("cpm_pic_host_map(%d, 0x%lx)\n", virq, hw);
 
-	get_irq_desc(virq)->status |= IRQ_LEVEL;
+	irq_to_desc(virq)->status |= IRQ_LEVEL;
 	set_irq_chip_and_handler(virq, &cpm_pic, handle_fasteoi_irq);
 	return 0;
 }