Add missing __init/__exit annotations to module init/exit funcs.

Link: https://lkml.kernel.org/r/20220906141210.132607-1-xiujianfeng@huawei.com

Fixes: 135b881e ("rv/reactor: Add the printk reactor")
Fixes: e88043c0 ("rv/reactor: Add the panic reactor")
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>