lisa._assets.kmodules.sched_tp: Add support for ARM PMU counters

FEATURE

Add support for tracing ARM PMU event counters by providing a dedicated
'perf_counter' trace event, associated with the sched_switch one.

The counters to be traced can be specified through module parameter,
as a list of comma-separated values denoting either names of generic
perf events or raw PMU counter ids, e.g.:

	insmod /data/local/sched_tp.ko features=event__perf_counter\
		generic_perf_events=cpu_cycles,inst_retired \
		pmu_raw_counters=35,36

The counters themselves will get activated on each online core at the
time of activation, with currently no support for hotplug.

The 'counter_id' filed of the 'perf_counter' trace event always represents
the PMU RAW counter id.

Signed-off-by: Beata Michalska <beata.michalska@arm.com>