[POWERPC] Add an optional device_node pointer to the irq_host

The majority of irq_host implementations (3 out of 4) are associated
with a device_node, and need to stash it somewhere. Rather than having
it somewhere different for each host, add an optional device_node pointer
to the irq_host structure.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/celleb/interrupt.c b/arch/powerpc/platforms/celleb/interrupt.c
index 98e6665..4ecdf06 100644
--- a/arch/powerpc/platforms/celleb/interrupt.c
+++ b/arch/powerpc/platforms/celleb/interrupt.c
@@ -242,7 +242,7 @@
 	ppc_md.get_irq = beatic_get_irq;
 
 	/* Allocate an irq host */
-	beatic_host = irq_alloc_host(IRQ_HOST_MAP_NOMAP, 0,
+	beatic_host = irq_alloc_host(NULL, IRQ_HOST_MAP_NOMAP, 0,
 					 &beatic_pic_host_ops,
 					 0);
 	BUG_ON(beatic_host == NULL);