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/ipic.c b/arch/powerpc/sysdev/ipic.c
index cb7689c..f042c1d 100644
--- a/arch/powerpc/sysdev/ipic.c
+++ b/arch/powerpc/sysdev/ipic.c
@@ -605,7 +605,7 @@
 {
 	struct ipic *ipic = ipic_from_irq(virq);
 	unsigned int src = ipic_irq_to_hw(virq);
-	struct irq_desc *desc = get_irq_desc(virq);
+	struct irq_desc *desc = irq_to_desc(virq);
 	unsigned int vold, vnew, edibit;
 
 	if (flow_type == IRQ_TYPE_NONE)