powerpc/kernel: Fix unbalanced refcount on RTAS device node

The RTAS device-tree node's refcount has been increased by one in
the function call of_find_node_by_name(), but it's missed to be
decreased by one in the error path. It leads to unbalanced refcount
on RTAS device-tree node.

This fixes above issue by decreasing RTAS device-tree node's refcount
in error path.
Signed-off-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/rtas.c

@@ -1158,6 +1158,7 @@ void __init rtas_initialize(void)
 	no_base = of_property_read_u32(rtas.dev, "linux,rtas-base", &base);
 	no_size = of_property_read_u32(rtas.dev, "rtas-size", &size);
 	if (no_base || no_size) {
+		of_node_put(rtas.dev);
 		rtas.dev = NULL;
 		return;
 	}