perf metricgroup: Remove unneeded semicolon

Eliminate the following coccicheck warning:
./tools/perf/util/metricgroup.c:382:3-4: Unneeded semicolon

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yang li <yang.lee@linux.alibaba.com>
Link: http://lore.kernel.org/lkml/1612165277-95878-1-git-send-email-yang.lee@linux.alibaba.com


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