perf kmem: Use evsel->tp_format and perf_sample

perf kmem: Use evsel->tp_format and perf_sample

To reduce the number of parameters passed to the various event handling
functions.

Cc: Andrey Wagin <avagin@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-p936ngz06yo5h797ggsm7xru@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>