perf list: Filter metrics too

perf list: Filter metrics too

When a filter is specified on the command line, filter the metrics too.

Before:

  % perf list foo
  List of pre-defined events (to be used in -e):

  Metric Groups:

  DSB:
    DSB_Coverage
         [Fraction of Uops delivered by the DSB (aka Decoded Icache; or Uop Cache)]
  ... more metrics ...

After:

% perf list foo

  List of pre-defined events (to be used in -e):

  Metric Groups:

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
LPU-Reference: 20190314225002.30108-1-andi@firstfloor.org
Link: https://lkml.kernel.org/n/tip-1y8oi2s8c4jhjtykgs5zvda1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>