perf tools: Replace needless mmap.h with what is needed, event.h

perf tools: Replace needless mmap.h with what is needed, event.h

The perf_sample struct definition and the event_attr_init() are in
util/event.h, but some places were getting it thru an otherwise needless
util/mmap.h header, fix it by including util/event.h directly.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-p1anwyjdbbvghrkl9dlxv7h5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>