perf list: Avoid extra : for --raw metrics

When printing the metrics raw, don't print : after the metricgroups.
This helps the command line completion to complete those too.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190628220737.13259-2-andi@firstfloor.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>