perf mem-events: Remove duplicate #undef

Remove duplicate '#undef E'.

Signed-off-by: Li Huafei <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Zhang Jinhao <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/mem-events.c

···
 };
 #undef E
 
-#undef E
-
 static char mem_loads_name[100];
 static bool mem_loads_name__init;