ARM: hisi: fix error handling and missing of_node_put

of_iomap() can return NULL which seems critical here and thus should be
explicitly flagged so that the cause of system halting can be understood.
As of_find_compatible_node() is returning a device node with refcount
incremented it must be explicitly decremented here.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: commit 7fda91e7 ("ARM: hisi: enable smp for HiP01")
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>

arch/arm/mach-hisi/hotplug.c

@@ -219,10 +219,10 @@ void hip01_set_cpu(int cpu, bool enable)
 
 	if (!ctrl_base) {
 		np = of_find_compatible_node(NULL, NULL, "hisilicon,hip01-sysctrl");
-		if (np)
-			ctrl_base = of_iomap(np, 0);
-		else
-			BUG();
+		BUG_ON(!np);
+		ctrl_base = of_iomap(np, 0);
+		of_node_put(np);
+		BUG_ON(!ctrl_base);
 	}
 
 	if (enable) {