ppc: Fix PowerBook HD led on ARCH=powerpc

Index: linux-work/drivers/ide/ppc/pmac.c
===================================================================
@@ -497,16 +497,19 @@
 	if (pmu_get_model() != PMU_KEYLARGO_BASED)
 		return 0;
 	
-	dt = find_devices("device-tree");
+	dt = of_find_node_by_path("/");
 	if (dt == NULL)
 		return 0;
 	model = (const char *)get_property(dt, "model", NULL);
 	if (model == NULL)
 		return 0;
 	if (strncmp(model, "PowerBook", strlen("PowerBook")) != 0 &&
-	    strncmp(model, "iBook", strlen("iBook")) != 0)
+	    strncmp(model, "iBook", strlen("iBook")) != 0) {
+		of_node_put(dt);
 	    	return 0;
-	
+	}
+	of_node_put(dt);
+
 	pmu_blink_on.complete = 1;
 	pmu_blink_off.complete = 1;
 	spin_lock_init(&pmu_blink_lock);