powerpc: Remove trival irq_host_ops.unmap

These all just clear chip or chipdata fields, which will be done
by the generic code when we call irq_free_descs.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/embedded6xx/flipper-pic.c

@@ -107,12 +107,6 @@ static int flipper_pic_map(struct irq_host *h, unsigned int virq,
 	return 0;
 }
 
-static void flipper_pic_unmap(struct irq_host *h, unsigned int irq)
-{
-	irq_set_chip_data(irq, NULL);
-	irq_set_chip(irq, NULL);
-}
-
 static int flipper_pic_match(struct irq_host *h, struct device_node *np)
 {
 	return 1;
@@ -121,7 +115,6 @@ static int flipper_pic_match(struct irq_host *h, struct device_node *np)
 
 static struct irq_host_ops flipper_irq_host_ops = {
 	.map = flipper_pic_map,
-	.unmap = flipper_pic_unmap,
 	.match = flipper_pic_match,
 };