tracing: remove deprecated TRACE_FORMAT

The TRACE_FORMAT macro has been deprecated by the TRACE_EVENT macro.
There are no more users. All new users must use the TRACE_EVENT macro.

[ Impact: remove old functionality ]

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>