perf tools: Remove misplaced __maybe_unused

All over the tree.

Cc: David Ahern <dsahern@gmail.com>
cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-8nzhnokxyp8y4v7gf0j00oyb@git.kernel.org


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