powerpc: Fix a number of sparse warnings

Address some of the trivial sparse warnings in arch/powerpc.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index c11c823..b19cd83 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -183,7 +183,7 @@
 	np = of_find_node_by_path("/");
 	naddr = of_n_addr_cells(np);
 	opprop = of_get_property(np, "platform-open-pic", &opplen);
-	if (opprop != 0) {
+	if (opprop != NULL) {
 		openpic_addr = of_read_number(opprop, naddr);
 		printk(KERN_DEBUG "OpenPIC addr: %lx\n", openpic_addr);
 	}