perf intel-pt: Add default config for pass-through branch enable

perf intel-pt: Add default config for pass-through branch enable

Branch tracing is enabled by default, so a fake config bit called 'pt'
(pass-through) was added to allow the 'branch enable' bit to have affect.
Add default config 'pt,branch' which will allow users to disable branch
tracing using 'branch=0' instead of having to specify 'pt,branch=0'.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1495786658-18063-12-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>