perf, x86: Fix key indexing in Pentium-4 PMU

Index 0-6 in p4_templates are reserved for common hardware
events. So p4_templates is arranged as below:

    0  -    6:  common hardware events
    7  -    N:  cache events
  N+1  -  ...:  other raw events

Reported-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268983738.13901.142.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>