perf/x86/amd: Generalize northbridge constraints code for family 15h

Generalize northbridge constraints code for family 10h so that
later we can reuse the same code path with other AMD processor
families that have the same northbridge event constraints.

Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Jacob Shin <jacob.shin@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360171589-6381-3-git-send-email-jacob.shin@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>