xtensa: report trax and perf counters in cpuinfo

Add 'trax' to the list of CPU features when xtensa core is configured
with TRAX.
Add 'perf' to the list of CPU features when xtensa core is configured
with perf counters and show the number of configured perf counters.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>