perf mem-events: Remove duplicate #undef

perf mem-events: Remove duplicate #undef

Remove duplicate '#undef E'.

Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhang Jinhao <zhangjinhao2@huawei.com>
Link: http://lore.kernel.org/lkml/20210616120339.219807-1-lihuafei1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>