bootconfig: init: Fix memblock leak in xbc_make_cmdline()

Free unused memblock in a error case to fix memblock leak
in xbc_make_cmdline().

Link: https://lkml.kernel.org/r/163177339181.682366.8713781325929549256.stgit@devnote2

Fixes: 51887d03 ("bootconfig: init: Allow admin to use bootconfig for kernel command line")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

init/main.c

@@ -382,6 +382,7 @@ static char * __init xbc_make_cmdline(const char *key)
 	ret = xbc_snprint_cmdline(new_cmdline, len + 1, root);
 	if (ret < 0 || ret > len) {
 		pr_err("Failed to print extra kernel cmdline.\n");
+		memblock_free_ptr(new_cmdline, len + 1);
 		return NULL;
 	}