tracing/probe: Fix to allow user to enable events on unloaded modules

Fix to allow user to enable probe events on unloaded modules.

This operations was allowed before commit 60d53e2c ("tracing/probe:
Split trace_event related data from trace_probe"), because if users
need to probe module init functions, they have to enable those probe
events before loading module.

Link: http://lkml.kernel.org/r/156879693733.31056.9331322616994665167.stgit@devnote2



Cc: stable@vger.kernel.org
Fixes: 60d53e2c ("tracing/probe: Split trace_event related data from trace_probe")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>