PM: tracing: Hide power_domain_target event under ARCH_OMAP2PLUS

PM: tracing: Hide power_domain_target event under ARCH_OMAP2PLUS

The power_domain_target event event is only called when CONFIG_OMAP2PLUS
is defined. As each event can take up to 5K regardless if they are used or
not, it's best not to define them when they are not used. Add #ifdef
around these events when they are not used.

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: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/20250612145408.415483176@goodmis.org
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>