tools/power/x86/intel-speed-select: Fix warning for perf_cap.cpu

tools/power/x86/intel-speed-select: Fix warning for perf_cap.cpu

Initialize perf_cap struct to avoid warning:

  CC      hfi-events.o
In function ‘process_hfi_event’,
    inlined from ‘handle_event’ at hfi-events.c:220:5:
hfi-events.c:184:9: warning: ‘perf_cap.cpu’ may be used
uninitialized [-Wmaybe-uninitialized]
  184 |         process_level_change(perf_cap->cpu);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
hfi-events.c: In function ‘handle_event’:
hfi-events.c:193:25: note: ‘perf_cap.cpu’ was declared here
  193 |         struct perf_cap perf_cap;
      |                         ^~~~~~~~

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20220511171208.211319-1-srinivas.pandruvada@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>