tracing: fix incorrect tracer freeing when opening tracing pipe

euler inclusion
category: bugfix
bugzilla: 9292
CVE: NA
---------------------------

Commit d716ff71 ("tracing: Remove taking of trace_types_lock in
pipe files") use the current tracer instead of the copy in
tracing_open_pipe(), but it forget to remove the freeing sentence in
the error path.

Fixes: d716ff71 ("tracing: Remove taking of trace_types_lock in pipe files")
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: Li Bin <huawei.libin@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>