perf/x86/intel: Add Tremont Topdown support

Tremont has four L1 Topdown events, TOPDOWN_FE_BOUND.ALL,
TOPDOWN_BAD_SPECULATION.ALL, TOPDOWN_BE_BOUND.ALL and
TOPDOWN_RETIRING.ALL. They are available on GP counters.

Export them to sysfs and facilitate the perf stat tool.

 $perf stat --topdown -- sleep 1

 Performance counter stats for 'sleep 1':

            retiring      bad speculation       frontend bound
backend bound
               24.9%                16.8%                31.7%
26.6%

       1.001224610 seconds time elapsed

       0.001150000 seconds user
       0.000000000 seconds sys

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1607457952-3519-1-git-send-email-kan.liang@linux.intel.com