kernel: events: Export perf_report_aux_output_id()

CoreSight trace being updated to use the perf_report_aux_output_id()
in a similar way to intel-pt.

This function in needs export visibility to allow it to be called from
kernel loadable modules, which CoreSight may configured to be built as.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230116124928.5440-12-mike.leach@linaro.org