tracing: Drop cpparg() macro

Drop the cpparg() macro that wraps CPP parameters. We already have
the PARAM() macro for that, no need to have several versions.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>