perf metric: Remove duplicate include

Remove duplicate header which is included twice.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200915081541.41004-1-yuehaibing@huawei.com


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