perf: Fix comments in PERF_MEM_LVL bitmask

This small patch fixes a mistake in the comments
for the PERF_MEM_LVL_* events. The L2, L3 bits simply
represent cache levels, not hits or misses. That is
encoded in PERF_MEM_LVL_MISS/PERF_MEM_LVL_HIT.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/20130405144941.GA30503@quad
Signed-off-by: Ingo Molnar <mingo@kernel.org>