ramoops: use DT reserved-memory bindings

Instead of a ramoops-specific node, use a child node of /reserved-memory.
This requires that of_platform_device_create() be explicitly called
for the node, though, since "/reserved-memory" does not have its own
"compatible" property.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 765390e..8aa1976 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -499,8 +499,24 @@
 
 static int __init of_platform_default_populate_init(void)
 {
-	if (of_have_populated_dt())
-		of_platform_default_populate(NULL, NULL, NULL);
+	struct device_node *node;
+
+	if (!of_have_populated_dt())
+		return -ENODEV;
+
+	/*
+	 * Handle ramoops explicitly, since it is inside /reserved-memory,
+	 * which lacks a "compatible" property.
+	 */
+	node = of_find_node_by_path("/reserved-memory");
+	if (node) {
+		node = of_find_compatible_node(node, NULL, "ramoops");
+		if (node)
+			of_platform_device_create(node, NULL, NULL);
+	}
+
+	/* Populate everything else. */
+	of_platform_default_populate(NULL, NULL, NULL);
 
 	return 0;
 }