perf/x86: Fix data source encoding issues for load latency/precise store

This patch fixes issues introuduce by Andi's previous patch 'Revamp PEBS'
series.

This patch fixes the following:

 - precise_store_data_hsw() encode the mem op type whenever we can
 - precise_store_data_hsw set the default data source correctly

 - 0 is not a valid init value for data source. Define PERF_MEM_NA as the
   default value

This bug was actually introduced by

    commit 722e76e6
    Author: Stephane Eranian <eranian@google.com>
    Date:   Thu May 15 17:56:44 2014 +0200

        fix Haswell precise store data source encoding

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1407785233-32193-4-git-send-email-eranian@google.com


Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: ak@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>