tools/bootconfig: Fix error return code in apply_xbc()

Fix to return a negative error code from the error handling case instead
of 0, as done elsewhere in this function.

Link: https://lkml.kernel.org/r/20210508034216.2277-1-thunder.leizhen@huawei.com

Fixes: a995e6bc ("tools/bootconfig: Fix to check the write failure correctly")
Reported-by: Hulk Robot <hulkci@huawei.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/bootconfig/main.c

@@ -399,6 +399,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	}
 	/* TODO: Ensure the @path is initramfs/initrd image */
 	if (fstat(fd, &stat) < 0) {
+		ret = -errno;
 		pr_err("Failed to get the size of %s\n", path);
 		goto out;
 	}