tools/bootconfig: Fix resource leak in apply_xbc()

Fix the @data and @fd allocations that are leaked in the error path of
apply_xbc().

Link: http://lkml.kernel.org/r/583a49c9-c27a-931d-e6c2-6f63a4b18bea@huawei.com



Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>