perf intel-pt: Fix TSC slip

perf intel-pt: Fix TSC slip

A TSC packet can slip past MTC packets so that the timestamp appears to
go backwards. One estimate is that can be up to about 40 CPU cycles,
which is certainly less than 0x1000 TSC ticks, but accept slippage an
order of magnitude more to be on the safe side.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 79b58424b821c ("perf tools: Add Intel PT support for decoding MTC packets")
Link: http://lkml.kernel.org/r/20190325135135.18348-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>