bootconfig: Add xbc_get_info() for the node information

Add xbc_get_info() API which allows user to get the
number of used xbc_nodes and the size of bootconfig
data. This is also useful for checking the bootconfig
is initialized or not.

Link: https://lkml.kernel.org/r/163177340877.682366.4360676589783197627.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
diff --git a/init/main.c b/init/main.c
index d894989..afaed80 100644
--- a/init/main.c
+++ b/init/main.c
@@ -450,6 +450,7 @@ static void __init setup_boot_config(void)
 			pr_err("Failed to parse bootconfig: %s at %d.\n",
 				msg, pos);
 	} else {
+		xbc_get_info(&ret, NULL);
 		pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret);
 		/* keys starting with "kernel." are passed via cmdline */
 		extra_command_line = xbc_make_cmdline("kernel");