powerpc/nvram: Search for nvram using compatible

As well as searching for nodes with type = "nvram", search for nodes
that have compatible = "nvram". This can't be converted into a single
call to of_find_compatible_node() with a non-NULL type, because that
searches for a node that has _both_ type & compatible = "nvram".
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/sysdev/mmio_nvram.c

@@ -115,6 +115,8 @@ int __init mmio_nvram_init(void)
 	int ret;
 
 	nvram_node = of_find_node_by_type(NULL, "nvram");
+	if (!nvram_node)
+		nvram_node = of_find_compatible_node(NULL, NULL, "nvram");
 	if (!nvram_node) {
 		printk(KERN_WARNING "nvram: no node found in device-tree\n");
 		return -ENODEV;