tracing: Simplify event_enable_func() goto_reg logic

Currently there's an "out_reg:" label that gets jumped to if there's no
parameters to process. Instead, make it a proper "if (param) { }" block as
there's not much to do for the parameter processing, and remove the
"out_reg:" label.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/20241219201345.354746196@goodmis.org


Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>