perf kvm stat: Set 'trace_cycles' as default event for 'perf kvm record' in powerpc

Use 'trace_imc/trace_cycles' as the default event for 'perf kvm record'
in powerpc.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lore.kernel.org/lkml/20190718181749.30612-3-anju@linux.vnet.ibm.com
[ Add missing pmu.h header, needed because this patch uses pmu_have_event() ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>