perf script: Move evname print code to process_event()

perf script: Move evname print code to process_event()

The print_sample_start() will be reused by other printing routine for
internal events like COMM, FORK and EXIT from next patch.  And because
they're not tied to a specific event, move the evname print code to its
caller.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1384752894-10974-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>