perf tools: Replace error() with pr_err()

To consolidate the error reporting facility.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-b41iot1094katoffdf19w9zk@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/util.h

@@ -16,7 +16,6 @@
 /* General helper functions */
 void usage(const char *err) __noreturn;
 void die(const char *err, ...) __noreturn __printf(1, 2);
-int error(const char *err, ...) __printf(1, 2);
 
 static inline void *zalloc(size_t size)
 {