x86, ds: fix bad ds_reset_pebs()

Ds_reset_pebs() passed the wrong qualifier to a shared function resulting
in a reset of bts, rather than pebs.

Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144605.206510000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>