tracing: Fix possible memory leak in __create_synth_event() error path

There's error paths in __create_synth_event() after the argv is allocated
that fail to free it. Add a jump to free it when necessary.

Link: https://lkml.kernel.org/r/20211209024317.11783-1-linmq006@gmail.com



Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
[ Fixed up the patch and change log ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>