perf tools: Drop prefetch.h

This was needed at the time before e66eed65 ("list: remove
prefetching from regular list iterators") where the list iterators did
prefetch elements. This turned out to be counter-productive and hurt
performance and they were removed. Which makes the prefetch.h header
unused so drop it.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rric@kernel.org>
Link: http://lkml.kernel.org/r/1391611914-26054-4-git-send-email-bp@alien8.deSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile.perf

@@ -219,7 +219,6 @@ LIB_H += util/include/linux/kernel.h
 LIB_H += util/include/linux/list.h
 LIB_H += util/include/linux/export.h
 LIB_H += util/include/linux/poison.h
-LIB_H += util/include/linux/prefetch.h
 LIB_H += util/include/linux/rbtree.h
 LIB_H += util/include/linux/rbtree_augmented.h
 LIB_H += util/include/linux/string.h

tools/perf/util/include/linux/list.h

 #include <linux/kernel.h>
-#include <linux/prefetch.h>
 
 #include "../../../../include/linux/list.h"
 

tools/perf/util/include/linux/prefetch.h

-#ifndef PERF_LINUX_PREFETCH_H
-#define PERF_LINUX_PREFETCH_H
-
-static inline void prefetch(void *a __attribute__((unused))) { }
-
-#endif