perf tools: Fix cache event name generation

If the event name is specified with all 3 components, the last one
overwrites the previous one during the name composing within the
parse_events_add_cache function.

Fixing this by properly adjusting the string index.

Reported-by: Joel Uckelman <joel@lightboxtechnologies.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joel Uckelman <joel@lightboxtechnologies.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LPU-Reference: 20120905175133.GA18352@krava.brq.redhat.com
[ committer note: Remove the newline fix, done already in 42e1fb77 ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>