perf tools: Add perf_pmu__format_bits()

perf tools: Add perf_pmu__format_bits()

Add perf_pmu__format_bits() to get the format bits for a PMU config
term.  Intel PT will use this to validate terms and to record format
bits to enable later interpreting the config from the attribute stored
in the perf.data file.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-15-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>